668945994 has 16 divisors (see below), whose sum is σ = 1338172032. Its totient is φ = 222935328.

The previous prime is 668945989. The next prime is 668945999. The reversal of 668945994 is 499549866.

It is an interprime number because it is at equal distance from previous prime (668945989) and next prime (668945999).

It is not an unprimeable number, because it can be changed into a prime (668945999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31902 + ... + 48534.

It is an arithmetic number, because the mean of its divisors is an integer number (83635752).

Almost surely, 2^668945994 is an apocalyptic number.

668945994 is an abundant number, since it is smaller than the sum of its proper divisors (669226038).

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

668945994 is a wasteful number, since it uses less digits than its factorization.

668945994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23341.

The product of its digits is 16796160, while the sum is 60.

The square root of 668945994 is about 25863.9902953895. The cubic root of 668945994 is about 874.5749201668.

The spelling of 668945994 in words is "six hundred sixty-eight million, nine hundred forty-five thousand, nine hundred ninety-four".