81604670872491 has 12 divisors (see below), whose sum is σ = 126940599135168. Its totient is φ = 50218258998384.

The previous prime is 81604670872471. The next prime is 81604670872507. The reversal of 81604670872491 is 19427807640618.

81604670872491 is a `hidden beast` number, since 8 + 1 + 6 + 0 + 4 + 6 + 70 + 8 + 72 + 491 = 666.

It is not a de Polignac number, because 81604670872491 - 2⁹ = 81604670871979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81604670872471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 348737909595 + ... + 348737909828.

It is an arithmetic number, because the mean of its divisors is an integer number (10578383261264).

Almost surely, 2^{81604670872491} is an apocalyptic number.

81604670872491 is a deficient number, since it is larger than the sum of its proper divisors (45335928262677).

81604670872491 is a wasteful number, since it uses less digits than its factorization.

81604670872491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 697475819442 (or 697475819439 counting only the distinct ones).

The product of its (nonzero) digits is 32514048, while the sum is 63.

The spelling of 81604670872491 in words is "eighty-one trillion, six hundred four billion, six hundred seventy million, eight hundred seventy-two thousand, four hundred ninety-one".