668909291 has 2 divisors, whose sum is σ = 668909292. Its totient is φ = 668909290.

The previous prime is 668909287. The next prime is 668909309. The reversal of 668909291 is 192909866.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 668909291 - 2² = 668909287 is a prime.

It is a super-2 number, since 2×668909291² = 894879279172245362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668909221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334454645 + 334454646.

It is an arithmetic number, because the mean of its divisors is an integer number (334454646).

Almost surely, 2^668909291 is an apocalyptic number.

668909291 is a deficient number, since it is larger than the sum of its proper divisors (1).

668909291 is an equidigital number, since it uses as much as digits as its factorization.

668909291 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 50.

The square root of 668909291 is about 25863.2807470359. The cubic root of 668909291 is about 874.5589247996.

The spelling of 668909291 in words is "six hundred sixty-eight million, nine hundred nine thousand, two hundred ninety-one".