21856524 has 12 divisors (see below), whose sum is σ = 50998584. Its totient is φ = 7285504.

The previous prime is 21856487. The next prime is 21856537. The reversal of 21856524 is 42565812.

It is a tau number, because it is divible by the number of its divisors (12).

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, 910677 + ... + 910700.

It is an arithmetic number, because the mean of its divisors is an integer number (4249882).

Almost surely, 2^21856524 is an apocalyptic number.

It is an amenable number.

21856524 is an abundant number, since it is smaller than the sum of its proper divisors (29142060).

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

21856524 is a wasteful number, since it uses less digits than its factorization.

21856524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1821384 (or 1821382 counting only the distinct ones).

The product of its digits is 19200, while the sum is 33.

The square root of 21856524 is about 4675.0961487439. The cubic root of 21856524 is about 279.5934746871.

The spelling of 21856524 in words is "twenty-one million, eight hundred fifty-six thousand, five hundred twenty-four".