643354561864 has 96 divisors (see below), whose sum is σ = 1487768290560. Its totient is φ = 259156800000.

The previous prime is 643354561807. The next prime is 643354561867. The reversal of 643354561864 is 468165453346.

643354561864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (643354561867) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4940389 + ... + 5068939.

It is an arithmetic number, because the mean of its divisors is an integer number (15497586360).

Almost surely, 2^643354561864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643354561864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (743884145280).

643354561864 is an abundant number, since it is smaller than the sum of its proper divisors (844413728696).

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

643354561864 is a wasteful number, since it uses less digits than its factorization.

643354561864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129339 (or 129328 counting only the distinct ones).

The product of its digits is 24883200, while the sum is 55.

The spelling of 643354561864 in words is "six hundred forty-three billion, three hundred fifty-four million, five hundred sixty-one thousand, eight hundred sixty-four".