20921968 has 20 divisors (see below), whose sum is σ = 42921360. Its totient is φ = 9845504.

The previous prime is 20921959. The next prime is 20921981. The reversal of 20921968 is 86912902.

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, 38188 + ... + 38731.

It is an arithmetic number, because the mean of its divisors is an integer number (2146068).

Almost surely, 2^20921968 is an apocalyptic number.

It is an amenable number.

20921968 is an abundant number, since it is smaller than the sum of its proper divisors (21999392).

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

20921968 is a wasteful number, since it uses less digits than its factorization.

20921968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76944 (or 76938 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 20921968 is about 4574.0537819313. The cubic root of 20921968 is about 275.5502722809.

The spelling of 20921968 in words is "twenty million, nine hundred twenty-one thousand, nine hundred sixty-eight".