21656252 has 6 divisors (see below), whose sum is σ = 37898448. Its totient is φ = 10828124.

The previous prime is 21656251. The next prime is 21656263. The reversal of 21656252 is 25265612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656251) by changing a digit.

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 as a sum of consecutive naturals, namely, 2707028 + ... + 2707035.

It is an arithmetic number, because the mean of its divisors is an integer number (6316408).

Almost surely, 2^21656252 is an apocalyptic number.

It is an amenable number.

21656252 is a deficient number, since it is larger than the sum of its proper divisors (16242196).

21656252 is a wasteful number, since it uses less digits than its factorization.

21656252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5414067 (or 5414065 counting only the distinct ones).

The product of its digits is 7200, while the sum is 29.

The square root of 21656252 is about 4653.6278321327. The cubic root of 21656252 is about 278.7368784670.

The spelling of 21656252 in words is "twenty-one million, six hundred fifty-six thousand, two hundred fifty-two".