21720968 has 32 divisors (see below), whose sum is σ = 43869600. Its totient is φ = 10044672.

The previous prime is 21720953. The next prime is 21720983. The reversal of 21720968 is 86902712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21720953) and next prime (21720983).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6671 + ... + 9377.

It is an arithmetic number, because the mean of its divisors is an integer number (1370925).

Almost surely, 2^21720968 is an apocalyptic number.

It is an amenable number.

21720968 is an abundant number, since it is smaller than the sum of its proper divisors (22148632).

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

21720968 is a wasteful number, since it uses less digits than its factorization.

21720968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2789 (or 2785 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 21720968 is about 4660.5759300756. The cubic root of 21720968 is about 279.0142548268.

The spelling of 21720968 in words is "twenty-one million, seven hundred twenty thousand, nine hundred sixty-eight".