640308168 has 48 divisors (see below), whose sum is σ = 1793972700. Its totient is φ = 206075520.

The previous prime is 640308167. The next prime is 640308217. The reversal of 640308168 is 861803046.

It is a happy number.

640308168 is a `hidden beast` number, since 640 + 3 + 0 + 8 + 1 + 6 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 640191204 + 116964 = 25302^2 + 342^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (640308167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 151243 + ... + 155418.

Almost surely, 2^640308168 is an apocalyptic number.

It is an amenable number.

640308168 is an abundant number, since it is smaller than the sum of its proper divisors (1153664532).

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

640308168 is a wasteful number, since it uses less digits than its factorization.

640308168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306702 (or 306695 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 640308168 is about 25304.3112532232. The cubic root of 640308168 is about 861.9121721159.

The spelling of 640308168 in words is "six hundred forty million, three hundred eight thousand, one hundred sixty-eight".