81173560657 has 4 divisors (see below), whose sum is σ = 92769783616. Its totient is φ = 69577337700.

The previous prime is 81173560639. The next prime is 81173560709. The reversal of 81173560657 is 75606537118.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81173560657 - 2⁷ = 81173560529 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 81173560657.

It is not an unprimeable number, because it can be changed into a prime (81173510657) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5798111469 + ... + 5798111482.

It is an arithmetic number, because the mean of its divisors is an integer number (23192445904).

Almost surely, 2^81173560657 is an apocalyptic number.

It is an amenable number.

81173560657 is a deficient number, since it is larger than the sum of its proper divisors (11596222959).

81173560657 is a wasteful number, since it uses less digits than its factorization.

81173560657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11596222958.

The product of its (nonzero) digits is 1058400, while the sum is 49.

The spelling of 81173560657 in words is "eighty-one billion, one hundred seventy-three million, five hundred sixty thousand, six hundred fifty-seven".