21665511006679 has 2 divisors, whose sum is σ = 21665511006680. Its totient is φ = 21665511006678.

The previous prime is 21665511006649. The next prime is 21665511006703. The reversal of 21665511006679 is 97660011556612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21665511006679 - 2²⁹ = 21664974135767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21665511006649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832755503339 + 10832755503340.

It is an arithmetic number, because the mean of its divisors is an integer number (10832755503340).

Almost surely, 2^{21665511006679} is an apocalyptic number.

21665511006679 is a deficient number, since it is larger than the sum of its proper divisors (1).

21665511006679 is an equidigital number, since it uses as much as digits as its factorization.

21665511006679 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4082400, while the sum is 55.

The spelling of 21665511006679 in words is "twenty-one trillion, six hundred sixty-five billion, five hundred eleven million, six thousand, six hundred seventy-nine".