668440645 has 16 divisors (see below), whose sum is σ = 812103552. Its totient is φ = 528131520.

The previous prime is 668440637. The next prime is 668440649. The reversal of 668440645 is 546044866.

It is not a de Polignac number, because 668440645 - 2³ = 668440637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668440649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 215274 + ... + 218356.

It is an arithmetic number, because the mean of its divisors is an integer number (50756472).

Almost surely, 2^668440645 is an apocalyptic number.

It is an amenable number.

668440645 is a deficient number, since it is larger than the sum of its proper divisors (143662907).

668440645 is a wasteful number, since it uses less digits than its factorization.

668440645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3612.

The product of its (nonzero) digits is 552960, while the sum is 43.

The square root of 668440645 is about 25854.2190947629. The cubic root of 668440645 is about 874.3546348697.

The spelling of 668440645 in words is "six hundred sixty-eight million, four hundred forty thousand, six hundred forty-five".