21264979 has 2 divisors, whose sum is σ = 21264980. Its totient is φ = 21264978.

The previous prime is 21264959. The next prime is 21265001. The reversal of 21264979 is 97946212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21264979 - 2⁷ = 21264851 is a prime.

It is not a weakly prime, because it can be changed into another prime (21264959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632489 + 10632490.

It is an arithmetic number, because the mean of its divisors is an integer number (10632490).

Almost surely, 2^21264979 is an apocalyptic number.

21264979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21264979 is an equidigital number, since it uses as much as digits as its factorization.

21264979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 21264979 is about 4611.3966431007. The cubic root of 21264979 is about 277.0479787606.

The spelling of 21264979 in words is "twenty-one million, two hundred sixty-four thousand, nine hundred seventy-nine".