643305820240 has 20 divisors (see below), whose sum is σ = 1495686032244. Its totient is φ = 257322328064.

The previous prime is 643305820217. The next prime is 643305820277. The reversal of 643305820240 is 42028503346.

It can be written as a sum of positive squares in 2 ways, for example, as 141667926544 + 501637893696 = 376388^2 + 708264^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 643305820240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4020661297 + ... + 4020661456.

Almost surely, 2^643305820240 is an apocalyptic number.

It is an amenable number.

643305820240 is an abundant number, since it is smaller than the sum of its proper divisors (852380212004).

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

643305820240 is a wasteful number, since it uses less digits than its factorization.

643305820240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8041322766 (or 8041322760 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 37.

The spelling of 643305820240 in words is "six hundred forty-three billion, three hundred five million, eight hundred twenty thousand, two hundred forty".