643781600720 has 40 divisors (see below), whose sum is σ = 1499218255944. Its totient is φ = 257095258112.

The previous prime is 643781600711. The next prime is 643781600731. The reversal of 643781600720 is 27006187346.

It can be written as a sum of positive squares in 4 ways, for example, as 3647193664 + 640134407056 = 60392^2 + 800084^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6471929 + ... + 6570648.

Almost surely, 2^643781600720 is an apocalyptic number.

It is an amenable number.

643781600720 is an abundant number, since it is smaller than the sum of its proper divisors (855436655224).

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

643781600720 is a wasteful number, since it uses less digits than its factorization.

643781600720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13043207 (or 13043201 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 44.

The spelling of 643781600720 in words is "six hundred forty-three billion, seven hundred eighty-one million, six hundred thousand, seven hundred twenty".