665661660497 has 2 divisors, whose sum is σ = 665661660498. Its totient is φ = 665661660496.

The previous prime is 665661660487. The next prime is 665661660509. The reversal of 665661660497 is 794066166566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 409543681936 + 256117978561 = 639956^2 + 506081^2 .

It is a cyclic number.

It is not a de Polignac number, because 665661660497 - 2⁴ = 665661660481 is a prime.

It is not a weakly prime, because it can be changed into another prime (665661660407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332830830248 + 332830830249.

It is an arithmetic number, because the mean of its divisors is an integer number (332830830249).

Almost surely, 2^665661660497 is an apocalyptic number.

It is an amenable number.

665661660497 is a deficient number, since it is larger than the sum of its proper divisors (1).

665661660497 is an equidigital number, since it uses as much as digits as its factorization.

665661660497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58786560, while the sum is 62.

The spelling of 665661660497 in words is "six hundred sixty-five billion, six hundred sixty-one million, six hundred sixty thousand, four hundred ninety-seven".