81158126161 has 24 divisors (see below), whose sum is σ = 95476917480. Its totient is φ = 68778243072.

The previous prime is 81158126057. The next prime is 81158126177. The reversal of 81158126161 is 16162185118.

It can be written as a sum of positive squares in 4 ways, for example, as 17272530625 + 63885595536 = 131425^2 + 252756^2 .

It is not a de Polignac number, because 81158126161 - 2⁹ = 81158125649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81158120161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5072971 + ... + 5088943.

It is an arithmetic number, because the mean of its divisors is an integer number (3978204895).

Almost surely, 2^81158126161 is an apocalyptic number.

It is an amenable number.

81158126161 is a deficient number, since it is larger than the sum of its proper divisors (14318791319).

81158126161 is a wasteful number, since it uses less digits than its factorization.

81158126161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17153 (or 17146 counting only the distinct ones).

The product of its digits is 23040, while the sum is 40.

The spelling of 81158126161 in words is "eighty-one billion, one hundred fifty-eight million, one hundred twenty-six thousand, one hundred sixty-one".