21975866 has 32 divisors (see below), whose sum is σ = 38688192. Its totient is φ = 9250560.

The previous prime is 21975851. The next prime is 21975911. The reversal of 21975866 is 66857912.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24620 + ... + 25496.

It is an arithmetic number, because the mean of its divisors is an integer number (1209006).

Almost surely, 2^21975866 is an apocalyptic number.

21975866 is a deficient number, since it is larger than the sum of its proper divisors (16712326).

21975866 is a wasteful number, since it uses less digits than its factorization.

21975866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974.

The product of its digits is 181440, while the sum is 44.

The square root of 21975866 is about 4687.8423608308. The cubic root of 21975866 is about 280.1014343378.

The spelling of 21975866 in words is "twenty-one million, nine hundred seventy-five thousand, eight hundred sixty-six".