21593879 has 2 divisors, whose sum is σ = 21593880. Its totient is φ = 21593878.

The previous prime is 21593867. The next prime is 21593917. The reversal of 21593879 is 97839512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21593879 - 2⁴ = 21593863 is a prime.

It is a super-2 number, since 2×21593879² = 932591220533282, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21593479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10796939 + 10796940.

It is an arithmetic number, because the mean of its divisors is an integer number (10796940).

Almost surely, 2^21593879 is an apocalyptic number.

21593879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21593879 is an equidigital number, since it uses as much as digits as its factorization.

21593879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 44.

The square root of 21593879 is about 4646.9214540381. The cubic root of 21593879 is about 278.4690208970.

The spelling of 21593879 in words is "twenty-one million, five hundred ninety-three thousand, eight hundred seventy-nine".