661731310161 has 16 divisors (see below), whose sum is σ = 980364163200. Its totient is φ = 441144540144.

The previous prime is 661731310127. The next prime is 661731310193. The reversal of 661731310161 is 161013137166.

661731310161 is a `hidden beast` number, since 6 + 617 + 3 + 1 + 31 + 0 + 1 + 6 + 1 = 666.

It is not a de Polignac number, because 661731310161 - 2⁷ = 661731310033 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661731410161) 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, 1116355 + ... + 1603031.

It is an arithmetic number, because the mean of its divisors is an integer number (61272760200).

Almost surely, 2^661731310161 is an apocalyptic number.

It is an amenable number.

661731310161 is a deficient number, since it is larger than the sum of its proper divisors (318632853039).

661731310161 is a wasteful number, since it uses less digits than its factorization.

661731310161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 537045 (or 537039 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The spelling of 661731310161 in words is "six hundred sixty-one billion, seven hundred thirty-one million, three hundred ten thousand, one hundred sixty-one".