643804 has 12 divisors (see below), whose sum is σ = 1287664. Its totient is φ = 275904.

The previous prime is 643781. The next prime is 643847. The reversal of 643804 is 408346.

643804 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11469 + ... + 11524.

2⁶⁴³⁸⁰⁴ is an apocalyptic number.

It is an amenable number.

643804 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

643804 is a wasteful number, since it uses less digits than its factorization.

643804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23004 (or 23002 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 643804 is about 802.3739776438. The cubic root of 643804 is about 86.3477893865.

The spelling of 643804 in words is "six hundred forty-three thousand, eight hundred four".