640735056 has 160 divisors (see below), whose sum is σ = 1992650240. Its totient is φ = 195955200.

The previous prime is 640735021. The next prime is 640735057. The reversal of 640735056 is 650537046.

640735056 is a `hidden beast` number, since 640 + 7 + 3 + 5 + 0 + 5 + 6 = 666.

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 640735056.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640735057) 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 31 ways as a sum of consecutive naturals, for example, 1521726 + ... + 1522146.

It is an arithmetic number, because the mean of its divisors is an integer number (12454064).

Almost surely, 2^640735056 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 640735056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (996325120).

640735056 is an abundant number, since it is smaller than the sum of its proper divisors (1351915184).

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

640735056 is a wasteful number, since it uses less digits than its factorization.

640735056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722 (or 710 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 36.

The square root of 640735056 is about 25312.7449321483. The cubic root of 640735056 is about 862.1036727320.

The spelling of 640735056 in words is "six hundred forty million, seven hundred thirty-five thousand, fifty-six".