21644632 has 16 divisors (see below), whose sum is σ = 40640760. Its totient is φ = 10807104.

The previous prime is 21644627. The next prime is 21644639. The reversal of 21644632 is 23644612.

It is a self number, because there is not a number n which added to its sum of digits gives 21644632.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21644639) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6148 + ... + 9004.

Almost surely, 2^21644632 is an apocalyptic number.

It is an amenable number.

21644632 is a deficient number, since it is larger than the sum of its proper divisors (18996128).

21644632 is a wasteful number, since it uses less digits than its factorization.

21644632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3810 (or 3806 counting only the distinct ones).

The product of its digits is 6912, while the sum is 28.

The square root of 21644632 is about 4652.3791762925. The cubic root of 21644632 is about 278.6870160070.

The spelling of 21644632 in words is "twenty-one million, six hundred forty-four thousand, six hundred thirty-two".