640281778986 has 32 divisors (see below), whose sum is σ = 1402645688640. Its totient is φ = 193946068736.

The previous prime is 640281778973. The next prime is 640281779009. The reversal of 640281778986 is 689877182046.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 108225876 + ... + 108231791.

It is an arithmetic number, because the mean of its divisors is an integer number (43832677770).

Almost surely, 2^640281778986 is an apocalyptic number.

640281778986 is an abundant number, since it is smaller than the sum of its proper divisors (762363909654).

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

640281778986 is a wasteful number, since it uses less digits than its factorization.

640281778986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216457718.

The product of its (nonzero) digits is 65028096, while the sum is 66.

The spelling of 640281778986 in words is "six hundred forty billion, two hundred eighty-one million, seven hundred seventy-eight thousand, nine hundred eighty-six".