81508505091164 has 12 divisors (see below), whose sum is σ = 147241170487488. Its totient is φ = 39439599237600.

The previous prime is 81508505091151. The next prime is 81508505091173. The reversal of 81508505091164 is 46119050580518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 328663326857 + ... + 328663327104.

It is an arithmetic number, because the mean of its divisors is an integer number (12270097540624).

Almost surely, 2^{81508505091164} is an apocalyptic number.

It is an amenable number.

81508505091164 is a deficient number, since it is larger than the sum of its proper divisors (65732665396324).

81508505091164 is a wasteful number, since it uses less digits than its factorization.

81508505091164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657326653996 (or 657326653994 counting only the distinct ones).

The product of its (nonzero) digits is 1728000, while the sum is 53.

The spelling of 81508505091164 in words is "eighty-one trillion, five hundred eight billion, five hundred five million, ninety-one thousand, one hundred sixty-four".