81985165981608 has 32 divisors (see below), whose sum is σ = 205760436039360. Its totient is φ = 27222052515840.

The previous prime is 81985165981571. The next prime is 81985165981651. The reversal of 81985165981608 is 80618956158918.

It is a self number, because there is not a number n which added to its sum of digits gives 81985165981608.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6646002748 + ... + 6646015083.

It is an arithmetic number, because the mean of its divisors is an integer number (6430013626230).

Almost surely, 2^{81985165981608} is an apocalyptic number.

It is an amenable number.

81985165981608 is an abundant number, since it is smaller than the sum of its proper divisors (123775270057752).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81985165981608 is a wasteful number, since it uses less digits than its factorization.

81985165981608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13292018097 (or 13292018093 counting only the distinct ones).

The product of its (nonzero) digits is 298598400, while the sum is 75.

The spelling of 81985165981608 in words is "eighty-one trillion, nine hundred eighty-five billion, one hundred sixty-five million, nine hundred eighty-one thousand, six hundred eight".