81049220761 has 2 divisors, whose sum is σ = 81049220762. Its totient is φ = 81049220760.

The previous prime is 81049220743. The next prime is 81049220767. The reversal of 81049220761 is 16702294018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69831233536 + 11217987225 = 264256^2 + 105915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81049220761 is a prime.

It is not a weakly prime, because it can be changed into another prime (81049220767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40524610380 + 40524610381.

It is an arithmetic number, because the mean of its divisors is an integer number (40524610381).

Almost surely, 2^81049220761 is an apocalyptic number.

It is an amenable number.

81049220761 is a deficient number, since it is larger than the sum of its proper divisors (1).

81049220761 is an equidigital number, since it uses as much as digits as its factorization.

81049220761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 40.

The spelling of 81049220761 in words is "eighty-one billion, forty-nine million, two hundred twenty thousand, seven hundred sixty-one".