643400960 has 72 divisors (see below), whose sum is σ = 1594381320. Its totient is φ = 248471552.

The previous prime is 643400929. The next prime is 643401037. The reversal of 643400960 is 69004346.

It can be written as a sum of positive squares in 4 ways, for example, as 1893376 + 641507584 = 1376^2 + 25328^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

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, 28454 + ... + 45786.

It is an arithmetic number, because the mean of its divisors is an integer number (22144185).

Almost surely, 2^643400960 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 643400960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (797190660).

643400960 is an abundant number, since it is smaller than the sum of its proper divisors (950980360).

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

643400960 is a wasteful number, since it uses less digits than its factorization.

643400960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17383 (or 17369 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 643400960 is about 25365.3495934907. The cubic root of 643400960 is about 863.2976688391.

The spelling of 643400960 in words is "six hundred forty-three million, four hundred thousand, nine hundred sixty".