640832256 has 288 divisors, whose sum is σ = 2060352000. Its totient is φ = 195858432.

The previous prime is 640832251. The next prime is 640832321. The reversal of 640832256 is 652238046.

640832256 is a `hidden beast` number, since 640 + 8 + 3 + 2 + 2 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

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

It is a self number, because there is not a number n which added to its sum of digits gives 640832256.

It is not an unprimeable number, because it can be changed into a prime (640832251) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4610235 + ... + 4610373.

It is an arithmetic number, because the mean of its divisors is an integer number (7154000).

Almost surely, 2^640832256 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 640832256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1030176000).

640832256 is an abundant number, since it is smaller than the sum of its proper divisors (1419519744).

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

640832256 is a wasteful number, since it uses less digits than its factorization.

640832256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 640832256 is about 25314.6648407598. The cubic root of 640832256 is about 862.1472644575.

The spelling of 640832256 in words is "six hundred forty million, eight hundred thirty-two thousand, two hundred fifty-six".