666131761665 has 48 divisors (see below), whose sum is σ = 1182510053712. Its totient is φ = 346760773632.

The previous prime is 666131761643. The next prime is 666131761679. The reversal of 666131761665 is 566167131666.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 2056713201 + 664075048464 = 45351^2 + 814908^2 .

It is not a de Polignac number, because 666131761665 - 2⁸ = 666131761409 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 263272 + ... + 1183881.

It is an arithmetic number, because the mean of its divisors is an integer number (24635626119).

Almost surely, 2^666131761665 is an apocalyptic number.

It is an amenable number.

666131761665 is a deficient number, since it is larger than the sum of its proper divisors (516378292047).

666131761665 is a wasteful number, since it uses less digits than its factorization.

666131761665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1447410 (or 1447407 counting only the distinct ones).

The product of its digits is 4898880, while the sum is 54.

The spelling of 666131761665 in words is "six hundred sixty-six billion, one hundred thirty-one million, seven hundred sixty-one thousand, six hundred sixty-five".