21979254013 has 2 divisors, whose sum is σ = 21979254014. Its totient is φ = 21979254012.

The previous prime is 21979253957. The next prime is 21979254103. The reversal of 21979254013 is 31045297912.

Together with next prime (21979254103) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21869381689 + 109872324 = 147883^2 + 10482^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21979254013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21979254113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10989627006 + 10989627007.

It is an arithmetic number, because the mean of its divisors is an integer number (10989627007).

Almost surely, 2^21979254013 is an apocalyptic number.

It is an amenable number.

21979254013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21979254013 is an equidigital number, since it uses as much as digits as its factorization.

21979254013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 43.

The spelling of 21979254013 in words is "twenty-one billion, nine hundred seventy-nine million, two hundred fifty-four thousand, thirteen".