21307912 has 32 divisors (see below), whose sum is σ = 41587200. Its totient is φ = 10224000.

The previous prime is 21307903. The next prime is 21307931. The reversal of 21307912 is 21970312.

It is a super-2 number, since 2×21307912² = 908054227599488, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37164 + ... + 37732.

It is an arithmetic number, because the mean of its divisors is an integer number (1299600).

Almost surely, 2^21307912 is an apocalyptic number.

It is an amenable number.

21307912 is a deficient number, since it is larger than the sum of its proper divisors (20279288).

21307912 is a wasteful number, since it uses less digits than its factorization.

21307912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 757 (or 753 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21307912 is about 4616.0493931499. The cubic root of 21307912 is about 277.2343024029.

The spelling of 21307912 in words is "twenty-one million, three hundred seven thousand, nine hundred twelve".