81996157697 has 2 divisors, whose sum is σ = 81996157698. Its totient is φ = 81996157696.

The previous prime is 81996157687. The next prime is 81996157721. The reversal of 81996157697 is 79675169918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48243486736 + 33752670961 = 219644^2 + 183719^2 .

It is a cyclic number.

It is not a de Polignac number, because 81996157697 - 2³⁴ = 64816288513 is a prime.

It is not a weakly prime, because it can be changed into another prime (81996157657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40998078848 + 40998078849.

It is an arithmetic number, because the mean of its divisors is an integer number (40998078849).

Almost surely, 2^81996157697 is an apocalyptic number.

It is an amenable number.

81996157697 is a deficient number, since it is larger than the sum of its proper divisors (1).

81996157697 is an equidigital number, since it uses as much as digits as its factorization.

81996157697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51438240, while the sum is 68.

The spelling of 81996157697 in words is "eighty-one billion, nine hundred ninety-six million, one hundred fifty-seven thousand, six hundred ninety-seven".