21631568 has 20 divisors (see below), whose sum is σ = 47898720. Its totient is φ = 9270624.

The previous prime is 21631541. The next prime is 21631573. The reversal of 21631568 is 86513612.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96458 + ... + 96681.

It is an arithmetic number, because the mean of its divisors is an integer number (2394936).

Almost surely, 2^21631568 is an apocalyptic number.

21631568 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21631568 is an abundant number, since it is smaller than the sum of its proper divisors (26267152).

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

21631568 is a wasteful number, since it uses less digits than its factorization.

21631568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193154 (or 193148 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 21631568 is about 4650.9749515559. The cubic root of 21631568 is about 278.6309358989.

The spelling of 21631568 in words is "twenty-one million, six hundred thirty-one thousand, five hundred sixty-eight".