21250979 has 2 divisors, whose sum is σ = 21250980. Its totient is φ = 21250978.

The previous prime is 21250961. The next prime is 21251017. The reversal of 21250979 is 97905212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21250979 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21250279) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625489 + 10625490.

It is an arithmetic number, because the mean of its divisors is an integer number (10625490).

Almost surely, 2^21250979 is an apocalyptic number.

21250979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250979 is an equidigital number, since it uses as much as digits as its factorization.

21250979 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11340, while the sum is 35.

The square root of 21250979 is about 4609.8784148825. The cubic root of 21250979 is about 276.9871663610.

The spelling of 21250979 in words is "twenty-one million, two hundred fifty thousand, nine hundred seventy-nine".