665156161717 has 4 divisors (see below), whose sum is σ = 666736105516. Its totient is φ = 663576217920.

The previous prime is 665156161679. The next prime is 665156161729. The reversal of 665156161717 is 717161651566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 717161651566 = 2 ⋅358580825783.

It can be written as a sum of positive squares in 2 ways, for example, as 18288234756 + 646867926961 = 135234^2 + 804281^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665156161717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665156161217) 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, 789971268 + ... + 789972109.

It is an arithmetic number, because the mean of its divisors is an integer number (166684026379).

Almost surely, 2^665156161717 is an apocalyptic number.

It is an amenable number.

665156161717 is a deficient number, since it is larger than the sum of its proper divisors (1579943799).

665156161717 is a wasteful number, since it uses less digits than its factorization.

665156161717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1579943798.

The product of its digits is 1587600, while the sum is 52.

The spelling of 665156161717 in words is "six hundred sixty-five billion, one hundred fifty-six million, one hundred sixty-one thousand, seven hundred seventeen".