21231000 has 192 divisors, whose sum is σ = 82255680. Its totient is φ = 4838400.

The previous prime is 21230969. The next prime is 21231029. The reversal of 21231000 is 13212.

21231000 = 90³ + 91³ + ... + 110³.

It is a happy number.

It is a super-2 number, since 2×21231000² = 901510722000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 62832 + ... + 63168.

It is an arithmetic number, because the mean of its divisors is an integer number (428415).

Almost surely, 2^21231000 is an apocalyptic number.

21231000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21231000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41127840).

21231000 is an abundant number, since it is smaller than the sum of its proper divisors (61024680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21231000 is a wasteful number, since it uses less digits than its factorization.

21231000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371 (or 354 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21231000 is about 4607.7109284329. The cubic root of 21231000 is about 276.9003364517.

Adding to 21231000 its reverse (13212), we get a palindrome (21244212).

The spelling of 21231000 in words is "twenty-one million, two hundred thirty-one thousand".