21979164 has 24 divisors (see below), whose sum is σ = 54301968. Its totient is φ = 6895360.

The previous prime is 21979163. The next prime is 21979169. The reversal of 21979164 is 46197912.

It is a congruent number.

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

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 7 ways as a sum of consecutive naturals, for example, 53667 + ... + 54074.

It is an arithmetic number, because the mean of its divisors is an integer number (2262582).

Almost surely, 2^21979164 is an apocalyptic number.

It is an amenable number.

21979164 is an abundant number, since it is smaller than the sum of its proper divisors (32322804).

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

21979164 is a wasteful number, since it uses less digits than its factorization.

21979164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107765 (or 107763 counting only the distinct ones).

The product of its digits is 27216, while the sum is 39.

The square root of 21979164 is about 4688.1941086094. The cubic root of 21979164 is about 280.1154455919.

The spelling of 21979164 in words is "twenty-one million, nine hundred seventy-nine thousand, one hundred sixty-four".