21628972 has 6 divisors (see below), whose sum is σ = 37850708. Its totient is φ = 10814484.

The previous prime is 21628969. The next prime is 21629009. The reversal of 21628972 is 27982612.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2703618 + ... + 2703625.

Almost surely, 2^21628972 is an apocalyptic number.

It is an amenable number.

21628972 is a deficient number, since it is larger than the sum of its proper divisors (16221736).

21628972 is a wasteful number, since it uses less digits than its factorization.

21628972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5407247 (or 5407245 counting only the distinct ones).

The product of its digits is 24192, while the sum is 37.

The square root of 21628972 is about 4650.6958619114. The cubic root of 21628972 is about 278.6197893060.

The spelling of 21628972 in words is "twenty-one million, six hundred twenty-eight thousand, nine hundred seventy-two".