81537775505 has 16 divisors (see below), whose sum is σ = 99975384000. Its totient is φ = 63820666560.

The previous prime is 81537775493. The next prime is 81537775507. The reversal of 81537775505 is 50557773518.

It is a de Polignac number, because none of the positive numbers 2^k-81537775505 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81537775507) 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, 592730 + ... + 717219.

It is an arithmetic number, because the mean of its divisors is an integer number (6248461500).

Almost surely, 2^81537775505 is an apocalyptic number.

It is an amenable number.

81537775505 is a deficient number, since it is larger than the sum of its proper divisors (18437608495).

81537775505 is a wasteful number, since it uses less digits than its factorization.

81537775505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1310224.

The product of its (nonzero) digits is 5145000, while the sum is 53.

The spelling of 81537775505 in words is "eighty-one billion, five hundred thirty-seven million, seven hundred seventy-five thousand, five hundred five".