640808 has 16 divisors (see below), whose sum is σ = 1373280. Its totient is φ = 274608.

The previous prime is 640793. The next prime is 640837. The reversal of 640808 is 808046.

640808 is nontrivially palindromic in base 6.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

640808 is a modest number, since divided by 808 gives 64 as remainder.

It is an unprimeable number.

640808 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5666 + ... + 5777.

It is an arithmetic number, because the mean of its divisors is an integer number (85830).

2⁶⁴⁰⁸⁰⁸ is an apocalyptic number.

It is an amenable number.

640808 is an abundant number, since it is smaller than the sum of its proper divisors (732472).

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

640808 is a wasteful number, since it uses less digits than its factorization.

640808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11456 (or 11452 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 640808 is about 800.5048407099. The cubic root of 640808 is about 86.2136386672.

The spelling of 640808 in words is "six hundred forty thousand, eight hundred eight".