21907986 has 16 divisors (see below), whose sum is σ = 44107968. Its totient is φ = 7254000.

The previous prime is 21907961. The next prime is 21908039. The reversal of 21907986 is 68970912.

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, 11185 + ... + 12996.

It is an arithmetic number, because the mean of its divisors is an integer number (2756748).

Almost surely, 2^21907986 is an apocalyptic number.

21907986 is an abundant number, since it is smaller than the sum of its proper divisors (22199982).

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

21907986 is a wasteful number, since it uses less digits than its factorization.

21907986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24337.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 21907986 is about 4680.5967568249. The cubic root of 21907986 is about 279.8127404380.

The spelling of 21907986 in words is "twenty-one million, nine hundred seven thousand, nine hundred eighty-six".