261666505531675 has 12 divisors (see below), whose sum is σ = 324518808794800. Its totient is φ = 209299435434720.

The previous prime is 261666505531657. The next prime is 261666505531679. The reversal of 261666505531675 is 576135505666162.

It is not a de Polignac number, because 261666505531675 - 2¹⁹ = 261666505007387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261666505531679) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 844066692 + ... + 844376641.

Almost surely, 2^{261666505531675} is an apocalyptic number.

261666505531675 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

261666505531675 is a deficient number, since it is larger than the sum of its proper divisors (62852303263125).

261666505531675 is a wasteful number, since it uses less digits than its factorization.

261666505531675 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1688449542 (or 1688449537 counting only the distinct ones).

The product of its (nonzero) digits is 204120000, while the sum is 64.

The spelling of 261666505531675 in words is "two hundred sixty-one trillion, six hundred sixty-six billion, five hundred five million, five hundred thirty-one thousand, six hundred seventy-five".