640479136 has 72 divisors (see below), whose sum is σ = 1412598852. Its totient is φ = 285542400.

The previous prime is 640479107. The next prime is 640479157. The reversal of 640479136 is 631974046.

640479136 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 596336400 + 44142736 = 24420^2 + 6644^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 203656 + ... + 206776.

Almost surely, 2^640479136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640479136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (706299426).

640479136 is an abundant number, since it is smaller than the sum of its proper divisors (772119716).

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

640479136 is a wasteful number, since it uses less digits than its factorization.

640479136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3206 (or 3187 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 40.

The square root of 640479136 is about 25307.6892663080. The cubic root of 640479136 is about 861.9888780387.

The spelling of 640479136 in words is "six hundred forty million, four hundred seventy-nine thousand, one hundred thirty-six".