21972880 has 20 divisors (see below), whose sum is σ = 51087132. Its totient is φ = 8789120.

The previous prime is 21972869. The next prime is 21972901. The reversal of 21972880 is 8827912.

It can be written as a sum of positive squares in 2 ways, for example, as 10575504 + 11397376 = 3252^2 + 3376^2 .

It is a tau number, because it is divible by the number of its divisors (20).

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, 137251 + ... + 137410.

Almost surely, 2^21972880 is an apocalyptic number.

21972880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21972880 is an abundant number, since it is smaller than the sum of its proper divisors (29114252).

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

21972880 is a wasteful number, since it uses less digits than its factorization.

21972880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274674 (or 274668 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 21972880 is about 4687.5238666059. The cubic root of 21972880 is about 280.0887473783.

The spelling of 21972880 in words is "twenty-one million, nine hundred seventy-two thousand, eight hundred eighty".