668391318 has 32 divisors (see below), whose sum is σ = 1697502720. Its totient is φ = 190968840.

The previous prime is 668391299. The next prime is 668391319. The reversal of 668391318 is 813193866.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668391319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 883738 + ... + 884493.

It is an arithmetic number, because the mean of its divisors is an integer number (53046960).

Almost surely, 2^668391318 is an apocalyptic number.

668391318 is an abundant number, since it is smaller than the sum of its proper divisors (1029111402).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

668391318 is a wasteful number, since it uses less digits than its factorization.

668391318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1768249 (or 1768243 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 668391318 is about 25853.2651322807. The cubic root of 668391318 is about 874.3331269257. Note that the first 3 decimals are identical.

The spelling of 668391318 in words is "six hundred sixty-eight million, three hundred ninety-one thousand, three hundred eighteen".