640393660516 has 9 divisors (see below), whose sum is σ = 1120691706771. Its totient is φ = 320196030012.

The previous prime is 640393660483. The next prime is 640393660531. The reversal of 640393660516 is 615066393046.

The square root of 640393660516 is 800246.

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

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640393660516.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1400431 + ... + 1800553.

Almost surely, 2^640393660516 is an apocalyptic number.

640393660516 is the 800246-th square number.

It is an amenable number.

640393660516 is a deficient number, since it is larger than the sum of its proper divisors (480298046255).

640393660516 is an frugal number, since it uses more digits than its factorization.

640393660516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 800250 (or 400125 counting only the distinct ones).

The product of its (nonzero) digits is 2099520, while the sum is 49.

Multiplying 640393660516 by its sum of digits (49), we get a square (31379289365284 = 5601722²).

The spelling of 640393660516 in words is "six hundred forty billion, three hundred ninety-three million, six hundred sixty thousand, five hundred sixteen".