21566944 has 24 divisors (see below), whose sum is σ = 48526128. Its totient is φ = 9242880.

The previous prime is 21566927. The next prime is 21566953. The reversal of 21566944 is 44966512.

It is a congruent number.

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, 47917 + ... + 48364.

It is an arithmetic number, because the mean of its divisors is an integer number (2021922).

Almost surely, 2^21566944 is an apocalyptic number.

It is an amenable number.

21566944 is an abundant number, since it is smaller than the sum of its proper divisors (26959184).

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

21566944 is an equidigital number, since it uses as much as digits as its factorization.

21566944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96298 (or 96290 counting only the distinct ones).

The product of its digits is 51840, while the sum is 37.

The square root of 21566944 is about 4644.0223944335. The cubic root of 21566944 is about 278.3531904829.

The spelling of 21566944 in words is "twenty-one million, five hundred sixty-six thousand, nine hundred forty-four".