21133928 has 32 divisors (see below), whose sum is σ = 42016800. Its totient is φ = 9937728.

The previous prime is 21133913. The next prime is 21133939. The reversal of 21133928 is 82933112.

It is a self number, because there is not a number n which added to its sum of digits gives 21133928.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24350 + ... + 25202.

It is an arithmetic number, because the mean of its divisors is an integer number (1313025).

Almost surely, 2^21133928 is an apocalyptic number.

It is an amenable number.

21133928 is a deficient number, since it is larger than the sum of its proper divisors (20882872).

21133928 is a wasteful number, since it uses less digits than its factorization.

21133928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1041 (or 1037 counting only the distinct ones).

The product of its digits is 2592, while the sum is 29.

The square root of 21133928 is about 4597.1652134767. The cubic root of 21133928 is about 276.4776787111.

The spelling of 21133928 in words is "twenty-one million, one hundred thirty-three thousand, nine hundred twenty-eight".