668198717 has 2 divisors, whose sum is σ = 668198718. Its totient is φ = 668198716.

The previous prime is 668198693. The next prime is 668198743. The reversal of 668198717 is 717891866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 343694521 + 324504196 = 18539^2 + 18014^2 .

It is a cyclic number.

It is not a de Polignac number, because 668198717 - 2¹⁶ = 668133181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668198747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334099358 + 334099359.

It is an arithmetic number, because the mean of its divisors is an integer number (334099359).

Almost surely, 2^668198717 is an apocalyptic number.

It is an amenable number.

668198717 is a deficient number, since it is larger than the sum of its proper divisors (1).

668198717 is an equidigital number, since it uses as much as digits as its factorization.

668198717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1016064, while the sum is 53.

The square root of 668198717 is about 25849.5399765644. The cubic root of 668198717 is about 874.2491373986.

The spelling of 668198717 in words is "six hundred sixty-eight million, one hundred ninety-eight thousand, seven hundred seventeen".