800 (number)

800s

• 801 = 3² × 89, Harshad number
• 802 = 2 × 401, sum of eight consecutive primes (83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), nontotient, happy number
• 803 = 11 × 73, sum of three consecutive primes (263 + 269 + 271), sum of nine consecutive primes (71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), Harshad number
• 804 = 2² × 3 × 67, nontotient, Harshad number
  • "The 804" is a local nickname for the Greater Richmond Region of the U.S. state of Virginia, derived from its telephone area code (although the area code covers a larger area).
• 805 = 5 × 7 × 23
• 806 = 2 × 13 × 31, sphenic number, nontotient, totient sum for first 51 integers, happy number
• 807 = 3 × 269
• 808 = 2³ × 101, strobogrammatic number^[1]
• 809 = prime number, Sophie Germain prime,^[2] Chen prime, Eisenstein prime with no imaginary part

810s

• 810 = 2 × 3⁴ × 5, Harshad number
• 811 = prime number, sum of five consecutive primes (151 + 157 + 163 + 167 + 173), Chen prime, happy number, the Mertens function of 811 returns 0
• 812 = 2² × 7 × 29, pronic number,^[3] the Mertens function of 812 returns 0
• 813 = 3 × 271
• 814 = 2 × 11 × 37, sphenic number, the Mertens function of 814 returns 0, nontotient
• 815 = 5 × 163
• 816 = 2⁴ × 3 × 17, tetrahedral number,^[4] Padovan number,^[5] Zuckerman number
• 817 = 19 × 43, sum of three consecutive primes (269 + 271 + 277), centered hexagonal number^[6]
• 818 = 2 × 409, nontotient, strobogrammatic number^[1]
• 819 = 3² × 7 × 13, square pyramidal number^[7]

820s

• 820 = 2² × 5 × 41, triangular number,^[8] Harshad number, happy number, repdigit (1111) in base 9
• 821 = prime number, twin prime, Eisenstein prime with no imaginary part, prime quadruplet with 823, 827, 829
• 822 = 2 × 3 × 137, sum of twelve consecutive primes (43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + 89 + 97), sphenic number, member of the Mian–Chowla sequence^[9]
• 823 = prime number, twin prime, the Mertens function of 823 returns 0, prime quadruplet with 821, 827, 829
• 824 = 2³ × 103, sum of ten consecutive primes (61 + 67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103), the Mertens function of 824 returns 0, nontotient
• 825 = 3 × 5² × 11, Smith number,^[10] the Mertens function of 825 returns 0, Harshad number
• 826 = 2 × 7 × 59, sphenic number
• 827 = prime number, twin prime, part of prime quadruplet with {821, 823, 829}, sum of seven consecutive primes (103 + 107 + 109 + 113 + 127 + 131 + 137), Chen prime, Eisenstein prime with no imaginary part, strictly non-palindromic number^[11]
• 828 = 2² × 3² × 23, Harshad number
• 829 = prime number, twin prime, part of prime quadruplet with {827, 823, 821}, sum of three consecutive primes (271 + 277 + 281), Chen prime

830s

• 830 = 2 × 5 × 83, sphenic number, sum of four consecutive primes (197 + 199 + 211 + 223), nontotient, totient sum for first 52 integers
• 831 = 3 × 277
• 832 = 2⁶ × 13, Harshad number
• 833 = 7² × 17
• 834 = 2 × 3 × 139, sphenic number, sum of six consecutive primes (127 + 131 + 137 + 139 + 149 + 151), nontotient
• 835 = 5 × 167, Motzkin number^[12]

• 836 = 2² × 11 × 19, weird number
• 837 = 3³ × 31
• 838 = 2 × 419
• 839 = prime number, safe prime,^[13] sum of five consecutive primes (157 + 163 + 167 + 173 + 179), Chen prime, Eisenstein prime with no imaginary part, highly cototient number^[14]

840s

• 840 = 2³ × 3 × 5 × 7, highly composite number,^[15] smallest numbers divisible by the numbers 1 to 8 (lowest common multiple of 1 to 8), sparsely totient number,^[16] Harshad number in base 2 through base 10
• 841 = 29² = 20² + 21², sum of three consecutive primes (277 + 281 + 283), sum of nine consecutive primes (73 + 79 + 83 + 89 + 97 + 101 + 103 + 107 + 109), centered square number,^[17] centered heptagonal number,^[18] centered octagonal number^[19]
• 842 = 2 × 421, nontotient
• 843 = 3 × 281, Lucas number^[20]
• 844 = 2² × 211, nontotient
• 845 = 5 × 13²
• 846 = 2 × 3² × 47, sum of eight consecutive primes (89 + 97 + 101 + 103 + 107 + 109 + 113 + 127), nontotient, Harshad number
• 847 = 7 × 11², happy number
• 848 = 2⁴ × 53
• 849 = 3 × 283, the Mertens function of 849 returns 0

850s

• 850 = 2 × 5² × 17, the Mertens function of 850 returns 0, nontotient, the maximum possible Fair Isaac credit score, country calling code for North Korea
• 851 = 23 × 37
• 852 = 2² × 3 × 71, pentagonal number,^[21] Smith number^[10]
  • country calling code for Hong Kong
• 853 = prime number, Perrin number,^[22] the Mertens function of 853 returns 0, average of first 853 prime numbers is an integer (sequence A045345 in the OEIS), strictly non-palindromic number, number of connected graphs with 7 nodes
  • country calling code for Macau
• 854 = 2 × 7 × 61, nontotient
• 855 = 3² × 5 × 19, decagonal number,^[23] centered cube number^[24]
  • country calling code for Cambodia
• 856 = 2³ × 107, nonagonal number,^[25] centered pentagonal number,^[26] happy number
  • country calling code for Laos
• 857 = prime number, sum of three consecutive primes (281 + 283 + 293), Chen prime, Eisenstein prime with no imaginary part
• 858 = 2 × 3 × 11 × 13, Giuga number^[27]
• 859 = prime number

860s

• 860 = 2² × 5 × 43, sum of four consecutive primes (199 + 211 + 223 + 227)
• 861 = 3 × 7 × 41, sphenic number, triangular number,^[8] hexagonal number,^[28] Smith number^[10]
• 862 = 2 × 431
• 863 = prime number, safe prime,^[13] sum of five consecutive primes (163 + 167 + 173 + 179 + 181), sum of seven consecutive primes (107 + 109 + 113 + 127 + 131 + 137 + 139), Chen prime, Eisenstein prime with no imaginary part
• 864 = 2⁵ × 3³, sum of a twin prime (431 + 433), sum of six consecutive primes (131 + 137 + 139 + 149 + 151 + 157), Harshad number
• 865 = 5 × 173,
• 866 = 2 × 433, nontotient
• 867 = 3 × 17²
• 868 = 2² × 7 × 31, nontotient
• 869 = 11 × 79, the Mertens function of 869 returns 0

870s

• 870 = 2 × 3 × 5 × 29, sum of ten consecutive primes (67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), pronic number,^[3] nontotient, sparsely totient number,^[16] Harshad number
  • This number is the magic constant of n×n normal magic square and n-queens problem for n = 12.
• 871 = 13 × 67
• 872 = 2³ × 109, nontotient
• 873 = 3² × 97, sum of the first six factorials from 1
• 874 = 2 × 19 × 23, sum of the first twenty-three primes, sum of the first seven factorials from 0, nontotient, Harshad number, happy number
• 875 = 5³ × 7
• 876 = 2² × 3 × 73
• 877 = prime number, Bell number,^[29] Chen prime, the Mertens function of 877 returns 0, strictly non-palindromic number.^[11]
• 878 = 2 × 439, nontotient
• 879 = 3 × 293

880s

• 880 = 2⁴ × 5 × 11, Harshad number; 148-gonal number; the number of n×n magic squares for n = 4.
  • country calling code for Bangladesh

• 881 = prime number, twin prime, sum of nine consecutive primes (79 + 83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), Chen prime, Eisenstein prime with no imaginary part, happy number
• 882 = 2 × 3² × 7², Harshad number, totient sum for first 53 integers
• 883 = prime number, twin prime, sum of three consecutive primes (283 + 293 + 307), the Mertens function of 883 returns 0
• 884 = 2² × 13 × 17, the Mertens function of 884 returns 0
• 885 = 3 × 5 × 59, sphenic number
• 886 = 2 × 443, the Mertens function of 886 returns 0
  • country calling code for Taiwan
• 887 = prime number followed by primal gap of 20, safe prime,^[13] Chen prime, Eisenstein prime with no imaginary part

• 888 = 2³ × 3 × 37, sum of eight consecutive primes (97 + 101 + 103 + 107 + 109 + 113 + 127 + 131), Harshad number, strobogrammatic number^[1]
• 889 = 7 × 127, the Mertens function of 889 returns 0

890s

• 890 = 2 × 5 × 89, sphenic number, sum of four consecutive primes (211 + 223 + 227 + 229), nontotient
• 891 = 3⁴ × 11, sum of five consecutive primes (167 + 173 + 179 + 181 + 191), octahedral number
• 892 = 2² × 223, nontotient
• 893 = 19 × 47, the Mertens function of 893 returns 0
  • Considered an unlucky number in Japan, because its digits read sequentially are the literal translation of yakuza.
• 894 = 2 × 3 × 149, sphenic number, nontotient
• 895 = 5 × 179, Smith number,^[10] Woodall number,^[30] the Mertens function of 895 returns 0
• 896 = 2⁷ × 7, sum of six consecutive primes (137 + 139 + 149 + 151 + 157 + 163), the Mertens function of 896 returns 0
• 897 = 3 × 13 × 23, sphenic number
• 898 = 2 × 449, the Mertens function of 898 returns 0, nontotient
• 899 = 29 × 31, happy number