21386928 has 40 divisors (see below), whose sum is σ = 55552000. Its totient is φ = 7089984.

The previous prime is 21386923. The next prime is 21386947. The reversal of 21386928 is 82968312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21386921) by changing a digit.

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, 8433 + ... + 10671.

It is an arithmetic number, because the mean of its divisors is an integer number (1388800).

Almost surely, 2^21386928 is an apocalyptic number.

It is an amenable number.

21386928 is an abundant number, since it is smaller than the sum of its proper divisors (34165072).

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

21386928 is a wasteful number, since it uses less digits than its factorization.

21386928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2449 (or 2443 counting only the distinct ones).

The product of its digits is 41472, while the sum is 39.

The square root of 21386928 is about 4624.6003070536. The cubic root of 21386928 is about 277.5765684337.

The spelling of 21386928 in words is "twenty-one million, three hundred eighty-six thousand, nine hundred twenty-eight".