665657717 has 2 divisors, whose sum is σ = 665657718. Its totient is φ = 665657716.

The previous prime is 665657711. The next prime is 665657719. The reversal of 665657717 is 717756566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 454798276 + 210859441 = 21326^2 + 14521^2 .

It is a cyclic number.

It is not a de Polignac number, because 665657717 - 2⁴ = 665657701 is a prime.

Together with 665657719, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665657711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332828858 + 332828859.

It is an arithmetic number, because the mean of its divisors is an integer number (332828859).

Almost surely, 2^665657717 is an apocalyptic number.

It is an amenable number.

665657717 is a deficient number, since it is larger than the sum of its proper divisors (1).

665657717 is an equidigital number, since it uses as much as digits as its factorization.

665657717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1852200, while the sum is 50.

The square root of 665657717 is about 25800.3433504285. The cubic root of 665657717 is about 873.1395428681.

The spelling of 665657717 in words is "six hundred sixty-five million, six hundred fifty-seven thousand, seven hundred seventeen".