100,000

100,001 to 199,999

200,000 to 299,999

• 206,265 – number of arc seconds in a radian (see also parsec)
• 207,360 – highly totient number^[3]
• 208,012 – Catalan number^[17]
• 208,335 – the largest number to be both triangular and square pyramidal
• 208,495 – Kaprekar number^[14]
• 221,760 – highly composite number^[5]
• 222,222 – repdigit
• 237,510 – harmonic divisor number^[4]
• 241,920 – highly totient number^[3]
• 242,060 – harmonic divisor number^[4]
• 248,832 – 12⁵, the smallest fifth power that can be represented as the sum of only 6 fifth powers
• 261,119 – Carol number^[18]
• 262,144 – 2¹⁸; exponential factorial of 4;^[19] a superperfect number^[20]
• 262,468 – Leyland number^[12]
• 263,167 – Kynea number^[21]
• 268,705 – Leyland number^[12]
• 274,177 – prime factor of F₆
• 277,200 – highly composite number^[5]
• 279,936 – 6⁷
• 280,859 – a six-digit prime number whose square (algebra) is tridigital.
• 293,547 – Wedderburn–Etherington number^[10]
• 294,685 – Markov number^[13]
• 298,320 – Keith number^[8]

300,000 to 399,999

• 310,572 – Motzkin number^[6]
• 317,811 – Fibonacci number^[9]
• 318,682 – Kaprekar number^[14]
• 326,981 – alternating factorial^[22]
• 329,967 – Kaprekar number^[14]
• 332,640 – highly composite number;^[5] harmonic divisor number^[4]
• 333,333 – repdigit
• 333,667 – sexy prime and unique prime^[23]
• 333,673 – sexy prime
• 333,679 – sexy prime
• 351,352 – Kaprekar number^[14]
• 355,419 – Keith number^[8]
• 356,643 – Kaprekar number^[14]
• 360,360 – harmonic divisor number;^[4] the smallest number divisible by all of the numbers 1 through 15
• 362,880 – 9!, highly totient number^[3]
• 370,261 – first prime followed by a prime gap of over 100
• 371,293 – 13⁵, palindromic in base 12 (15AA51₁₂)
• 389,305 – self-descriptive number in base 7
• 390,313 – Kaprekar number^[14]
• 390,625 – 5⁸
• 397,585 – Leyland number^[12]

400,000 to 499,999

• 409,113 – sum of the first nine factorials
• 422,481 – smallest number whose fourth power is the sum of three smaller fourth powers
• 423,393 – Leyland number^[12]
• 426,389 – Markov number^[13]
• 426,569 – cyclic number in base 12
• 437,760 to 440,319 – any of these numbers will cause the Apple II+ and Apple //e computers to crash to a monitor prompt when entered at the Basic prompt, due to a short-cut in the Applesoft code programming of the overflow test when evaluating 16 bit numbers.^[24] Entering 440000 at the prompt has been used to hack games that are protected against entering commands at the prompt after the game is loaded.
• 444,444 – repdigit
• 461,539 – Kaprekar number^[14]
• 466,830 – Kaprekar number^[14]
• 470,832 – Pell number^[16]
• 483,840 – highly totient number^[3]
• 498,960 – highly composite number^[5]
• 499,393 – Markov number^[13]
• 499,500 – Kaprekar number^[14]

500,000 to 599,999

• 500,500 – Kaprekar number,^[14] sum of first 1000 integers
• 509,203 – Riesel number^[25]
• 510,510 – the product of the first seven prime numbers, thus the seventh primorial^[26]
• 514,229 – Fibonacci prime,^[27] Markov number^[13]
• 524,287 – Mersenne prime^[11]
• 524,288 – 2¹⁹
• 524,649 – Leyland number^[12]
• 531,441 – 3¹²
• 533,169 – Leyland number^[12]
• 533,170 – Kaprekar number^[14]
• 537,824 – 14⁵
• 539,400 – harmonic divisor number^[4]
• 548,834 – equal to the sum of the sixth powers of its digits
• 554,400 – highly composite number^[5]
• 555,555 – repdigit

600,000 to 699,999

• 604,800 – number of seconds in a week
• 646,018 – Markov number^[13]
• 665,280 – highly composite number^[5]
• 666,666 – repdigit
• 676,157 – Wedderburn–Etherington number^[10]
• 678,570 – Bell number^[7]
• 694,280 – Keith number^[8]
• 695,520 – harmonic divisor number^[4]

700,000 to 799,999

• 720,720 – superior highly composite number;^[28] colossally abundant number;^[29] the smallest number divisible by all the numbers 1 through 16
• 725,760 – highly totient number^[3]
• 726,180 – harmonic divisor number^[4]
• 742,900 – Catalan number^[17]
• 753,480 – harmonic divisor number^[4]
• 759,375 – 15⁵
• 765,623 – emirp, Friedman number 5⁶ × 7² − 6 ÷ 3
• 777,777 – repdigit, smallest natural number requiring 20 syllables in American English, 22 in British English

800,000 to 899,999

• 823,543 – 7⁷
• 832,040 – Fibonacci number^[9]
• 853,467 – Motzkin number^[6]
• 873,612 – 1¹ + 2² + 3³ + 4⁴ + 5⁵ + 6⁶ + 7⁷
• 888,888 – repdigit

900,000 to 999,999

• 909,091 – unique prime
• 925,765 – Markov number^[13]
• 925,993 – Keith number^[8]
• 950,976 – harmonic divisor number^[4]
• 967,680 – highly totient number^[3]
• 999,983 – largest 6-digit prime number
• 999,999 – repdigit. Rational numbers with denominators 7 and 13 have 6-digit repetends when expressed in decimal form, because 999999 is divisible by 7 and by 13.