21556916 has 12 divisors (see below), whose sum is σ = 37806720. Its totient is φ = 10755000.

The previous prime is 21556907. The next prime is 21556921. The reversal of 21556916 is 61965512.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 3710 + ... + 7541.

It is an arithmetic number, because the mean of its divisors is an integer number (3150560).

Almost surely, 2^21556916 is an apocalyptic number.

It is an amenable number.

21556916 is a deficient number, since it is larger than the sum of its proper divisors (16249804).

21556916 is a wasteful number, since it uses less digits than its factorization.

21556916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11734 (or 11732 counting only the distinct ones).

The product of its digits is 16200, while the sum is 35.

The square root of 21556916 is about 4642.9426014113. The cubic root of 21556916 is about 278.3100417560.

The spelling of 21556916 in words is "twenty-one million, five hundred fifty-six thousand, nine hundred sixteen".