21631564 has 12 divisors (see below), whose sum is σ = 39160800. Its totient is φ = 10442768.

The previous prime is 21631541. The next prime is 21631573. The reversal of 21631564 is 46513612.

It is a super-2 number, since 2×21631564² = 935849122172192, which contains 22 as substring.

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, 93124 + ... + 93355.

It is an arithmetic number, because the mean of its divisors is an integer number (3263400).

Almost surely, 2^21631564 is an apocalyptic number.

It is an amenable number.

21631564 is a deficient number, since it is larger than the sum of its proper divisors (17529236).

21631564 is a wasteful number, since it uses less digits than its factorization.

21631564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186512 (or 186510 counting only the distinct ones).

The product of its digits is 4320, while the sum is 28.

The square root of 21631564 is about 4650.9745215385. The cubic root of 21631564 is about 278.6309187245.

The spelling of 21631564 in words is "twenty-one million, six hundred thirty-one thousand, five hundred sixty-four".