81538145773 has 16 divisors (see below), whose sum is σ = 94709846016. Its totient is φ = 68752298880.

The previous prime is 81538145729. The next prime is 81538145803. The reversal of 81538145773 is 37754183518.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81538145773 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81538145773.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538142773) 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, 12598 + ... + 404023.

It is an arithmetic number, because the mean of its divisors is an integer number (5919365376).

Almost surely, 2^81538145773 is an apocalyptic number.

It is an amenable number.

81538145773 is a deficient number, since it is larger than the sum of its proper divisors (13171700243).

81538145773 is a wasteful number, since it uses less digits than its factorization.

81538145773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417084.

The product of its digits is 2822400, while the sum is 52.

The spelling of 81538145773 in words is "eighty-one billion, five hundred thirty-eight million, one hundred forty-five thousand, seven hundred seventy-three".