640804 has 6 divisors (see below), whose sum is σ = 1121414. Its totient is φ = 320400.

The previous prime is 640793. The next prime is 640837. The reversal of 640804 is 408046.

It can be written as a sum of positive squares in only one way, i.e., 419904 + 220900 = 648^2 + 470^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80097 + ... + 80104.

2⁶⁴⁰⁸⁰⁴ is an apocalyptic number.

It is an amenable number.

640804 is a deficient number, since it is larger than the sum of its proper divisors (480610).

640804 is a wasteful number, since it uses less digits than its factorization.

640804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160205 (or 160203 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 640804 is about 800.5023422826. The cubic root of 640804 is about 86.2134592815.

It can be divided in two parts, 640 and 804, that added together give a square (1444 = 38²).

The spelling of 640804 in words is "six hundred forty thousand, eight hundred four".