21028928 has 28 divisors (see below), whose sum is σ = 42623232. Its totient is φ = 10289280.

The previous prime is 21028919. The next prime is 21028933. The reversal of 21028928 is 82982012.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21028894 and 21028903.

It is a congruent number.

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, 488 + ... + 6503.

Almost surely, 2^21028928 is an apocalyptic number.

It is an amenable number.

21028928 is an abundant number, since it is smaller than the sum of its proper divisors (21594304).

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

21028928 is an equidigital number, since it uses as much as digits as its factorization.

21028928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7050 (or 7040 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21028928 is about 4585.7309122974. The cubic root of 21028928 is about 276.0190423045.

The spelling of 21028928 in words is "twenty-one million, twenty-eight thousand, nine hundred twenty-eight".