640331816 has 16 divisors (see below), whose sum is σ = 1201420500. Its totient is φ = 319953024.

The previous prime is 640331777. The next prime is 640331851. The reversal of 640331816 is 618133046.

It can be written as a sum of positive squares in 2 ways, for example, as 598780900 + 41550916 = 24470^2 + 6446^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13445 + ... + 38228.

Almost surely, 2^640331816 is an apocalyptic number.

It is an amenable number.

640331816 is a deficient number, since it is larger than the sum of its proper divisors (561088684).

640331816 is a wasteful number, since it uses less digits than its factorization.

640331816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53228 (or 53224 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 640331816 is about 25304.7785210620. The cubic root of 640331816 is about 861.9227827609.

The spelling of 640331816 in words is "six hundred forty million, three hundred thirty-one thousand, eight hundred sixteen".