21251856 has 20 divisors (see below), whose sum is σ = 54900752. Its totient is φ = 7083936.

The previous prime is 21251843. The next prime is 21251863. The reversal of 21251856 is 65815212.

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, 221326 + ... + 221421.

Almost surely, 2^21251856 is an apocalyptic number.

It is an amenable number.

21251856 is an abundant number, since it is smaller than the sum of its proper divisors (33648896).

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

21251856 is a wasteful number, since it uses less digits than its factorization.

21251856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442758 (or 442752 counting only the distinct ones).

The product of its digits is 4800, while the sum is 30.

The square root of 21251856 is about 4609.9735357158. The cubic root of 21251856 is about 276.9909766075.

The spelling of 21251856 in words is "twenty-one million, two hundred fifty-one thousand, eight hundred fifty-six".