81537305563 has 16 divisors (see below), whose sum is σ = 94190007744. Its totient is φ = 69136404480.

The previous prime is 81537305539. The next prime is 81537305567. The reversal of 81537305563 is 36550373518.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81537305563 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81537305567) 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, 1492083 + ... + 1545763.

It is an arithmetic number, because the mean of its divisors is an integer number (5886875484).

Almost surely, 2^81537305563 is an apocalyptic number.

81537305563 is a deficient number, since it is larger than the sum of its proper divisors (12652702181).

81537305563 is a wasteful number, since it uses less digits than its factorization.

81537305563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56022.

The product of its (nonzero) digits is 1134000, while the sum is 46.

The spelling of 81537305563 in words is "eighty-one billion, five hundred thirty-seven million, three hundred five thousand, five hundred sixty-three".