81566173038 has 32 divisors (see below), whose sum is σ = 186965150976. Its totient is φ = 23238597888.

The previous prime is 81566172979. The next prime is 81566173061. The reversal of 81566173038 is 83037166518.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2735956 + ... + 2765607.

It is an arithmetic number, because the mean of its divisors is an integer number (5842660968).

Almost surely, 2^81566173038 is an apocalyptic number.

81566173038 is an abundant number, since it is smaller than the sum of its proper divisors (105398977938).

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

81566173038 is a wasteful number, since it uses less digits than its factorization.

81566173038 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5501928.

The product of its (nonzero) digits is 725760, while the sum is 48.

The spelling of 81566173038 in words is "eighty-one billion, five hundred sixty-six million, one hundred seventy-three thousand, thirty-eight".