640854685156 has 81 divisors (see below), whose sum is σ = 1315664047971. Its totient is φ = 272341666800.

The previous prime is 640854685103. The next prime is 640854685181. The reversal of 640854685156 is 651586458046.

The square root of 640854685156 is 800534.

It is a perfect power (a square), and thus also a powerful number.

It is a self number, because there is not a number n which added to its sum of digits gives 640854685156.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2364777301 + ... + 2364777571.

Almost surely, 2^640854685156 is an apocalyptic number.

640854685156 is the 800534-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640854685156

640854685156 is an abundant number, since it is smaller than the sum of its proper divisors (674809362815).

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

640854685156 is an equidigital number, since it uses as much as digits as its factorization.

640854685156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982 (or 491 counting only the distinct ones).

The product of its (nonzero) digits is 27648000, while the sum is 58.

The spelling of 640854685156 in words is "six hundred forty billion, eight hundred fifty-four million, six hundred eighty-five thousand, one hundred fifty-six".