21979968 has 28 divisors (see below), whose sum is σ = 58155840. Its totient is φ = 7326592.

The previous prime is 21979957. The next prime is 21980003. The reversal of 21979968 is 86997912.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21979968.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57048 + ... + 57431.

Almost surely, 2^21979968 is an apocalyptic number.

It is an amenable number.

21979968 is an abundant number, since it is smaller than the sum of its proper divisors (36175872).

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

21979968 is a wasteful number, since it uses less digits than its factorization.

21979968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114494 (or 114484 counting only the distinct ones).

The product of its digits is 489888, while the sum is 51.

The square root of 21979968 is about 4688.2798551281. The cubic root of 21979968 is about 280.1188611005.

The spelling of 21979968 in words is "twenty-one million, nine hundred seventy-nine thousand, nine hundred sixty-eight".