21156656 has 20 divisors (see below), whose sum is σ = 41992104. Its totient is φ = 10320000.

The previous prime is 21156647. The next prime is 21156661. The reversal of 21156656 is 65665112.

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, 15470 + ... + 16781.

Almost surely, 2^21156656 is an apocalyptic number.

It is an amenable number.

21156656 is a deficient number, since it is larger than the sum of its proper divisors (20835448).

21156656 is a wasteful number, since it uses less digits than its factorization.

21156656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32300 (or 32294 counting only the distinct ones).

The product of its digits is 10800, while the sum is 32.

The square root of 21156656 is about 4599.6365073775. The cubic root of 21156656 is about 276.5767537378.

It can be divided in two parts, 21156 and 656, that added together give a palindrome (21812).

The spelling of 21156656 in words is "twenty-one million, one hundred fifty-six thousand, six hundred fifty-six".