645808 has 20 divisors (see below), whose sum is σ = 1263808. Its totient is φ = 319680.

The previous prime is 645803. The next prime is 645833. The reversal of 645808 is 808546.

645808 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 645808.

It is not an unprimeable number, because it can be changed into a prime (645803) 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, 2785 + ... + 3007.

2⁶⁴⁵⁸⁰⁸ is an apocalyptic number.

It is an amenable number.

645808 is a deficient number, since it is larger than the sum of its proper divisors (618000).

645808 is a wasteful number, since it uses less digits than its factorization.

645808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 412 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 31.

The square root of 645808 is about 803.6218015958. The cubic root of 645808 is about 86.4372895737.

The spelling of 645808 in words is "six hundred forty-five thousand, eight hundred eight".