665177213121 has 4 divisors (see below), whose sum is σ = 886902950832. Its totient is φ = 443451475412.

The previous prime is 665177213093. The next prime is 665177213179. The reversal of 665177213121 is 121312771566.

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 665177213121 - 2⁵ = 665177213089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665177213191) 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, 110862868851 + ... + 110862868856.

It is an arithmetic number, because the mean of its divisors is an integer number (221725737708).

Almost surely, 2^665177213121 is an apocalyptic number.

It is an amenable number.

665177213121 is a deficient number, since it is larger than the sum of its proper divisors (221725737711).

665177213121 is a wasteful number, since it uses less digits than its factorization.

665177213121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221725737710.

The product of its digits is 105840, while the sum is 42.

Adding to 665177213121 its reverse (121312771566), we get a palindrome (786489984687).

The spelling of 665177213121 in words is "six hundred sixty-five billion, one hundred seventy-seven million, two hundred thirteen thousand, one hundred twenty-one".