21099928 has 32 divisors (see below), whose sum is σ = 41025600. Its totient is φ = 10166688.

The previous prime is 21099917. The next prime is 21099943. The reversal of 21099928 is 82999012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28183 + ... + 28921.

It is an arithmetic number, because the mean of its divisors is an integer number (1282050).

Almost surely, 2^21099928 is an apocalyptic number.

It is an amenable number.

21099928 is a deficient number, since it is larger than the sum of its proper divisors (19925672).

21099928 is a wasteful number, since it uses less digits than its factorization.

21099928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 871 (or 867 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 21099928 is about 4593.4657939295. The cubic root of 21099928 is about 276.3293345165.

The spelling of 21099928 in words is "twenty-one million, ninety-nine thousand, nine hundred twenty-eight".