21056856 has 32 divisors (see below), whose sum is σ = 52876800. Its totient is φ = 6987680.

The previous prime is 21056839. The next prime is 21056869. The reversal of 21056856 is 65865012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3901 + ... + 7571.

It is an arithmetic number, because the mean of its divisors is an integer number (1652400).

Almost surely, 2^21056856 is an apocalyptic number.

It is an amenable number.

21056856 is an abundant number, since it is smaller than the sum of its proper divisors (31819944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21056856 is a wasteful number, since it uses less digits than its factorization.

21056856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3919 (or 3915 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 21056856 is about 4588.7749999319. The cubic root of 21056856 is about 276.1411796093.

It can be divided in two parts, 21056 and 856, that added together give a palindrome (21912).

The spelling of 21056856 in words is "twenty-one million, fifty-six thousand, eight hundred fifty-six".