668392717 has 2 divisors, whose sum is σ = 668392718. Its totient is φ = 668392716.

The previous prime is 668392691. The next prime is 668392721. The reversal of 668392717 is 717293866.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 482724841 + 185667876 = 21971^2 + 13626^2 .

It is a cyclic number.

It is not a de Polignac number, because 668392717 - 2⁷ = 668392589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668302717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334196358 + 334196359.

It is an arithmetic number, because the mean of its divisors is an integer number (334196359).

Almost surely, 2^668392717 is an apocalyptic number.

It is an amenable number.

668392717 is a deficient number, since it is larger than the sum of its proper divisors (1).

668392717 is an equidigital number, since it uses as much as digits as its factorization.

668392717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 762048, while the sum is 49.

The square root of 668392717 is about 25853.2921888103. The cubic root of 668392717 is about 874.3337369432. Note that the first 3 decimals are identical.

The spelling of 668392717 in words is "six hundred sixty-eight million, three hundred ninety-two thousand, seven hundred seventeen".