643404 has 12 divisors (see below), whose sum is σ = 1501304. Its totient is φ = 214464.

The previous prime is 643403. The next prime is 643421. The reversal of 643404 is 404346.

It is a tau number, because it is divible by the number of its divisors (12).

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643404.

It is not an unprimeable number, because it can be changed into a prime (643403) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26797 + ... + 26820.

2⁶⁴³⁴⁰⁴ is an apocalyptic number.

It is an amenable number.

643404 is an abundant number, since it is smaller than the sum of its proper divisors (857900).

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

643404 is a wasteful number, since it uses less digits than its factorization.

643404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53624 (or 53622 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 643404 is about 802.1246785881. The cubic root of 643404 is about 86.3299028500.

The spelling of 643404 in words is "six hundred forty-three thousand, four hundred four".