21930979 has 6 divisors (see below), whose sum is σ = 25511604. Its totient is φ = 18797940.

The previous prime is 21930917. The next prime is 21930991. The reversal of 21930979 is 97903912.

It is not a de Polignac number, because 21930979 - 2⁷ = 21930851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21930379) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 223737 + ... + 223834.

It is an arithmetic number, because the mean of its divisors is an integer number (4251934).

Almost surely, 2^21930979 is an apocalyptic number.

21930979 is a deficient number, since it is larger than the sum of its proper divisors (3580625).

21930979 is an equidigital number, since it uses as much as digits as its factorization.

21930979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447585 (or 447578 counting only the distinct ones).

The product of its (nonzero) digits is 30618, while the sum is 40.

The square root of 21930979 is about 4683.0523165987. The cubic root of 21930979 is about 279.9105964566.

The spelling of 21930979 in words is "twenty-one million, nine hundred thirty thousand, nine hundred seventy-nine".