21939960 has 64 divisors (see below), whose sum is σ = 75225600. Its totient is φ = 5014656.

The previous prime is 21939937. The next prime is 21939977. The reversal of 21939960 is 6993912.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12220 + ... + 13899.

It is an arithmetic number, because the mean of its divisors is an integer number (1175400).

Almost surely, 2^21939960 is an apocalyptic number.

21939960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21939960 is an abundant number, since it is smaller than the sum of its proper divisors (53285640).

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

21939960 is a wasteful number, since it uses less digits than its factorization.

21939960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26140 (or 26136 counting only the distinct ones).

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 21939960 is about 4684.0111016094. The cubic root of 21939960 is about 279.9488001622.

The spelling of 21939960 in words is "twenty-one million, nine hundred thirty-nine thousand, nine hundred sixty".