665660156661 has 6 divisors (see below), whose sum is σ = 961509115190. Its totient is φ = 443773437768.

The previous prime is 665660156647. The next prime is 665660156669. The reversal of 665660156661 is 166651066566.

It can be written as a sum of positive squares in only one way, i.e., 619518539025 + 46141617636 = 787095^2 + 214806^2 .

It is not a de Polignac number, because 665660156661 - 2⁷ = 665660156533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 665660156598 and 665660156607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665660156669) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36981119806 + ... + 36981119823.

Almost surely, 2^665660156661 is an apocalyptic number.

It is an amenable number.

665660156661 is a deficient number, since it is larger than the sum of its proper divisors (295848958529).

665660156661 is a wasteful number, since it uses less digits than its factorization.

665660156661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73962239635 (or 73962239632 counting only the distinct ones).

The product of its (nonzero) digits is 6998400, while the sum is 54.

The spelling of 665660156661 in words is "six hundred sixty-five billion, six hundred sixty million, one hundred fifty-six thousand, six hundred sixty-one".