21665564034013 has 2 divisors, whose sum is σ = 21665564034014. Its totient is φ = 21665564034012.

The previous prime is 21665564033987. The next prime is 21665564034041. The reversal of 21665564034013 is 31043046556612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11840329596484 + 9825234437529 = 3440978^2 + 3134523^2 .

It is a cyclic number.

It is not a de Polignac number, because 21665564034013 - 2¹³ = 21665564025821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21665564034713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832782017006 + 10832782017007.

It is an arithmetic number, because the mean of its divisors is an integer number (10832782017007).

Almost surely, 2^{21665564034013} is an apocalyptic number.

It is an amenable number.

21665564034013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21665564034013 is an equidigital number, since it uses as much as digits as its factorization.

21665564034013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1555200, while the sum is 46.

The spelling of 21665564034013 in words is "twenty-one trillion, six hundred sixty-five billion, five hundred sixty-four million, thirty-four thousand, thirteen".