21937728 has 28 divisors (see below), whose sum is σ = 58044080. Its totient is φ = 7312512.

The previous prime is 21937709. The next prime is 21937753. The reversal of 21937728 is 82773912.

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, 56938 + ... + 57321.

Almost surely, 2^21937728 is an apocalyptic number.

It is an amenable number.

21937728 is an abundant number, since it is smaller than the sum of its proper divisors (36106352).

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

21937728 is a wasteful number, since it uses less digits than its factorization.

21937728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114274 (or 114264 counting only the distinct ones).

The product of its digits is 42336, while the sum is 39.

The square root of 21937728 is about 4683.7728382149. The cubic root of 21937728 is about 279.9393065728.

The spelling of 21937728 in words is "twenty-one million, nine hundred thirty-seven thousand, seven hundred twenty-eight".