81331391679 has 16 divisors (see below), whose sum is σ = 109036531200. Its totient is φ = 53924403456.

The previous prime is 81331391651. The next prime is 81331391731. The reversal of 81331391679 is 97619313318.

It is not a de Polignac number, because 81331391679 - 2⁸ = 81331391423 is a prime.

It is a super-2 number, since 2×81331391679² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81331391179) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 300042 + ... + 502680.

It is an arithmetic number, because the mean of its divisors is an integer number (6814783200).

Almost surely, 2^81331391679 is an apocalyptic number.

81331391679 is a deficient number, since it is larger than the sum of its proper divisors (27705139521).

81331391679 is a wasteful number, since it uses less digits than its factorization.

81331391679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203374.

The product of its digits is 734832, while the sum is 51.

The spelling of 81331391679 in words is "eighty-one billion, three hundred thirty-one million, three hundred ninety-one thousand, six hundred seventy-nine".