643710963856 has 15 divisors (see below), whose sum is σ = 1247196210451. Its totient is φ = 321853877296.

The previous prime is 643710963817. The next prime is 643710963869. The reversal of 643710963856 is 658369017346.

It is a happy number.

The square root of 643710963856 is 802316.

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 643710963856.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 3108975 + ... + 3309553.

Almost surely, 2^643710963856 is an apocalyptic number.

643710963856 is the 802316-th square number.

It is an amenable number.

643710963856 is a deficient number, since it is larger than the sum of its proper divisors (603485246595).

643710963856 is an frugal number, since it uses more digits than its factorization.

643710963856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401166 (or 200581 counting only the distinct ones).

The product of its (nonzero) digits is 19595520, while the sum is 58.

The spelling of 643710963856 in words is "six hundred forty-three billion, seven hundred ten million, nine hundred sixty-three thousand, eight hundred fifty-six".