640221720556 has 48 divisors (see below), whose sum is σ = 1270739820672. Its totient is φ = 279674524800.

The previous prime is 640221720461. The next prime is 640221720557. The reversal of 640221720556 is 655027122046.

It is not an unprimeable number, because it can be changed into a prime (640221720557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2527566 + ... + 2769301.

It is an arithmetic number, because the mean of its divisors is an integer number (26473746264).

Almost surely, 2^640221720556 is an apocalyptic number.

It is an amenable number.

640221720556 is a deficient number, since it is larger than the sum of its proper divisors (630518100116).

640221720556 is a wasteful number, since it uses less digits than its factorization.

640221720556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5296990 (or 5296988 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 40.

The spelling of 640221720556 in words is "six hundred forty billion, two hundred twenty-one million, seven hundred twenty thousand, five hundred fifty-six".