90,000

90,000 (ninety thousand) is the natural number following 89,999 and preceding 90,001. It is the sum of the cubes of the first 24 positive integers, and is the square of 300.

Selected numbers in the range 90,000–99,999

 * 90,625 = the only five-digit automorphic number: 906252 = 8212890625
 * 91,125 = 453
 * 91,144 = Fine number
 * 92,205 = number of 23-bead necklaces (turning over is allowed) where complements are equivalent
 * 92,706 = There is a math puzzle called KAYAK + KAYAK + KAYAK + KAYAK + KAYAK + KAYAK = SPORT, where each letter represents a digit. When one solves the puzzle, KAYAK = 15451, and when one added this up, SPORT = 92,706.
 * 93,312 = Leyland number: 66 + 66. Also a 3-smooth number.
 * 94,249 = palindromic square: 3072
 * 94,932 = Leyland number: 75 + 57
 * 95,121 = Kaprekar number: 951212 = 9048004641; 90480 + 04641 = 95121
 * 95,420 = number of 22-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed
 * 96,557 = Markov number: 52 + 64662 + 965572 = 3 × 5 × 6466 × 96557
 * 97,336 = 463, the largest 5-digit cube
 * 98,304 = 3-smooth number
 * 99,066 = largest number whose square uses all of the decimal digits once: 990662 = 9814072356. It is also strobogrammatic in decimal.
 * 99,856 = 3162, the largest 5-digit square
 * 99,991 = largest five-digit prime number
 * 99,999 = repdigit, Kaprekar number: 999992 = 9999800001; 99998 + 00001 = 99999

Primes
There are 879 prime numbers between 90000 and 100000.