21968164 has 12 divisors (see below), whose sum is σ = 38477488. Its totient is φ = 10974600.

The previous prime is 21968159. The next prime is 21968171. The reversal of 21968164 is 46186912.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6679 + ... + 9409.

Almost surely, 2^21968164 is an apocalyptic number.

It is an amenable number.

21968164 is a deficient number, since it is larger than the sum of its proper divisors (16509324).

21968164 is a wasteful number, since it uses less digits than its factorization.

21968164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4746 (or 4744 counting only the distinct ones).

The product of its digits is 20736, while the sum is 37.

The square root of 21968164 is about 4687.0208021727. The cubic root of 21968164 is about 280.0687076286.

The spelling of 21968164 in words is "twenty-one million, nine hundred sixty-eight thousand, one hundred sixty-four".