21920856 has 32 divisors (see below), whose sum is σ = 55204800. Its totient is φ = 7253280.

The previous prime is 21920831. The next prime is 21920869. The reversal of 21920856 is 65802912.

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 7 ways as a sum of consecutive naturals, for example, 51 + ... + 6621.

It is an arithmetic number, because the mean of its divisors is an integer number (1725150).

Almost surely, 2^21920856 is an apocalyptic number.

It is an amenable number.

21920856 is an abundant number, since it is smaller than the sum of its proper divisors (33283944).

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

21920856 is a wasteful number, since it uses less digits than its factorization.

21920856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6719 (or 6715 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21920856 is about 4681.9713796648. The cubic root of 21920856 is about 279.8675223642.

The spelling of 21920856 in words is "twenty-one million, nine hundred twenty thousand, eight hundred fifty-six".