640456344 has 96 divisors (see below), whose sum is σ = 1974585600. Its totient is φ = 185634240.

The previous prime is 640456343. The next prime is 640456361. The reversal of 640456344 is 443654046.

640456344 is a `hidden beast` number, since 640 + 4 + 5 + 6 + 3 + 4 + 4 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 640456299 and 640456308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640456343) 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 23 ways as a sum of consecutive naturals, for example, 637 + ... + 35795.

It is an arithmetic number, because the mean of its divisors is an integer number (20568600).

Almost surely, 2^640456344 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 640456344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (987292800).

640456344 is an abundant number, since it is smaller than the sum of its proper divisors (1334129256).

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

640456344 is a wasteful number, since it uses less digits than its factorization.

640456344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35205 (or 35198 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 36.

The square root of 640456344 is about 25307.2389643754. The cubic root of 640456344 is about 861.9786530459.

The spelling of 640456344 in words is "six hundred forty million, four hundred fifty-six thousand, three hundred forty-four".