640087656 has 96 divisors (see below), whose sum is σ = 1819107360. Its totient is φ = 186551424.

The previous prime is 640087627. The next prime is 640087661. The reversal of 640087656 is 656780046.

It is a happy number.

640087656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 109791 + ... + 115473.

It is an arithmetic number, because the mean of its divisors is an integer number (18949035).

Almost surely, 2^640087656 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 640087656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (909553680).

640087656 is an abundant number, since it is smaller than the sum of its proper divisors (1179019704).

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

640087656 is a wasteful number, since it uses less digits than its factorization.

640087656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5743 (or 5720 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The square root of 640087656 is about 25299.9536758469. The cubic root of 640087656 is about 861.8132177849.

The spelling of 640087656 in words is "six hundred forty million, eighty-seven thousand, six hundred fifty-six".