81368661618679 has 2 divisors, whose sum is σ = 81368661618680. Its totient is φ = 81368661618678.

The previous prime is 81368661618631. The next prime is 81368661618701. The reversal of 81368661618679 is 97681616686318.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81368661618679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81368661658679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40684330809339 + 40684330809340.

It is an arithmetic number, because the mean of its divisors is an integer number (40684330809340).

Almost surely, 2^{81368661618679} is an apocalyptic number.

81368661618679 is a deficient number, since it is larger than the sum of its proper divisors (1).

81368661618679 is an equidigital number, since it uses as much as digits as its factorization.

81368661618679 is an evil number, because the sum of its binary digits is even.

The product of its digits is 752467968, while the sum is 76.

The spelling of 81368661618679 in words is "eighty-one trillion, three hundred sixty-eight billion, six hundred sixty-one million, six hundred eighteen thousand, six hundred seventy-nine".