81680446774037 has 2 divisors, whose sum is σ = 81680446774038. Its totient is φ = 81680446774036.

The previous prime is 81680446774021. The next prime is 81680446774049. The reversal of 81680446774037 is 73047764408618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51136100204401 + 30544346569636 = 7150951^2 + 5526694^2 .

It is a cyclic number.

It is not a de Polignac number, because 81680446774037 - 2⁴ = 81680446774021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81680446774007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40840223387018 + 40840223387019.

It is an arithmetic number, because the mean of its divisors is an integer number (40840223387019).

Almost surely, 2^{81680446774037} is an apocalyptic number.

It is an amenable number.

81680446774037 is a deficient number, since it is larger than the sum of its proper divisors (1).

81680446774037 is an equidigital number, since it uses as much as digits as its factorization.

81680446774037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 151732224, while the sum is 65.

The spelling of 81680446774037 in words is "eighty-one trillion, six hundred eighty billion, four hundred forty-six million, seven hundred seventy-four thousand, thirty-seven".