21979168 has 24 divisors (see below), whose sum is σ = 45154368. Its totient is φ = 10511424.

The previous prime is 21979163. The next prime is 21979169. The reversal of 21979168 is 86197912.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21979163) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14196 + ... + 15667.

It is an arithmetic number, because the mean of its divisors is an integer number (1881432).

Almost surely, 2^21979168 is an apocalyptic number.

It is an amenable number.

21979168 is an abundant number, since it is smaller than the sum of its proper divisors (23175200).

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

21979168 is a wasteful number, since it uses less digits than its factorization.

21979168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29896 (or 29888 counting only the distinct ones).

The product of its digits is 54432, while the sum is 43.

The square root of 21979168 is about 4688.1945352129. The cubic root of 21979168 is about 280.1154625846.

The spelling of 21979168 in words is "twenty-one million, nine hundred seventy-nine thousand, one hundred sixty-eight".