668613917 has 2 divisors, whose sum is σ = 668613918. Its totient is φ = 668613916.

The previous prime is 668613899. The next prime is 668613941. The reversal of 668613917 is 719316866.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 657717316 + 10896601 = 25646^2 + 3301^2 .

It is a cyclic number.

It is not a de Polignac number, because 668613917 - 2⁶ = 668613853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668613947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334306958 + 334306959.

It is an arithmetic number, because the mean of its divisors is an integer number (334306959).

Almost surely, 2^668613917 is an apocalyptic number.

It is an amenable number.

668613917 is a deficient number, since it is larger than the sum of its proper divisors (1).

668613917 is an equidigital number, since it uses as much as digits as its factorization.

668613917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 47.

The square root of 668613917 is about 25857.5698200740. The cubic root of 668613917 is about 874.4301778960.

The spelling of 668613917 in words is "six hundred sixty-eight million, six hundred thirteen thousand, nine hundred seventeen".