21956545979 has 2 divisors, whose sum is σ = 21956545980. Its totient is φ = 21956545978.

The previous prime is 21956545943. The next prime is 21956546011. The reversal of 21956545979 is 97954565912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21956545979 - 2¹⁶ = 21956480443 is a prime.

It is a super-2 number, since 2×21956545979² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21956545379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978272989 + 10978272990.

It is an arithmetic number, because the mean of its divisors is an integer number (10978272990).

Almost surely, 2^21956545979 is an apocalyptic number.

21956545979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956545979 is an equidigital number, since it uses as much as digits as its factorization.

21956545979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30618000, while the sum is 62.

The spelling of 21956545979 in words is "twenty-one billion, nine hundred fifty-six million, five hundred forty-five thousand, nine hundred seventy-nine".