21975972 has 12 divisors (see below), whose sum is σ = 51277296. Its totient is φ = 7325320.

The previous prime is 21975949. The next prime is 21976001. The reversal of 21975972 is 27957912.

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

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 3 ways as a sum of consecutive naturals, for example, 915654 + ... + 915677.

It is an arithmetic number, because the mean of its divisors is an integer number (4273108).

Almost surely, 2^21975972 is an apocalyptic number.

It is an amenable number.

21975972 is an abundant number, since it is smaller than the sum of its proper divisors (29301324).

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

21975972 is a wasteful number, since it uses less digits than its factorization.

21975972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1831338 (or 1831336 counting only the distinct ones).

The product of its digits is 79380, while the sum is 42.

The square root of 21975972 is about 4687.8536666581. The cubic root of 21975972 is about 280.1018846910.

The spelling of 21975972 in words is "twenty-one million, nine hundred seventy-five thousand, nine hundred seventy-two".