81368661618571 has 2 divisors, whose sum is σ = 81368661618572. Its totient is φ = 81368661618570.

The previous prime is 81368661618547. The next prime is 81368661618631. The reversal of 81368661618571 is 17581616686318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81368661618571 - 2⁷ = 81368661618443 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81368661618497 and 81368661618506.

It is not a weakly prime, because it can be changed into another prime (81368661628571) 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, 40684330809285 + 40684330809286.

It is an arithmetic number, because the mean of its divisors is an integer number (40684330809286).

Almost surely, 2^{81368661618571} is an apocalyptic number.

81368661618571 is a deficient number, since it is larger than the sum of its proper divisors (1).

81368661618571 is an equidigital number, since it uses as much as digits as its factorization.

81368661618571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69672960, while the sum is 67.

The spelling of 81368661618571 in words is "eighty-one trillion, three hundred sixty-eight billion, six hundred sixty-one million, six hundred eighteen thousand, five hundred seventy-one".