21525979 has 2 divisors, whose sum is σ = 21525980. Its totient is φ = 21525978.

The previous prime is 21525937. The next prime is 21525989. The reversal of 21525979 is 97952512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21525979 - 2⁹ = 21525467 is a prime.

It is a super-3 number, since 3×21525979³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21525989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10762989 + 10762990.

It is an arithmetic number, because the mean of its divisors is an integer number (10762990).

Almost surely, 2^21525979 is an apocalyptic number.

21525979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21525979 is an equidigital number, since it uses as much as digits as its factorization.

21525979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56700, while the sum is 40.

The square root of 21525979 is about 4639.6097896267. The cubic root of 21525979 is about 278.1768408857.

The spelling of 21525979 in words is "twenty-one million, five hundred twenty-five thousand, nine hundred seventy-nine".