21606980 has 24 divisors (see below), whose sum is σ = 46146240. Its totient is φ = 8495840.

The previous prime is 21606979. The next prime is 21606997. The reversal of 21606980 is 8960612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7976 + ... + 10335.

It is an arithmetic number, because the mean of its divisors is an integer number (1922760).

Almost surely, 2^21606980 is an apocalyptic number.

21606980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21606980 is an abundant number, since it is smaller than the sum of its proper divisors (24539260).

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

21606980 is a wasteful number, since it uses less digits than its factorization.

21606980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18379 (or 18377 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 21606980 is about 4648.3308832311. The cubic root of 21606980 is about 278.5253252028.

The spelling of 21606980 in words is "twenty-one million, six hundred six thousand, nine hundred eighty".