21979580 has 48 divisors (see below), whose sum is σ = 55534080. Its totient is φ = 7138368.

The previous prime is 21979571. The next prime is 21979603. The reversal of 21979580 is 8597912.

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, 1472 + ... + 6791.

It is an arithmetic number, because the mean of its divisors is an integer number (1156960).

Almost surely, 2^21979580 is an apocalyptic number.

21979580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21979580 is an abundant number, since it is smaller than the sum of its proper divisors (33554500).

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

21979580 is a wasteful number, since it uses less digits than its factorization.

21979580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8298 (or 8296 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 21979580 is about 4688.2384751631. The cubic root of 21979580 is about 280.1172128306.

The spelling of 21979580 in words is "twenty-one million, nine hundred seventy-nine thousand, five hundred eighty".