645806 has 16 divisors (see below), whose sum is σ = 1117824. Its totient is φ = 274104.

The previous prime is 645803. The next prime is 645833. The reversal of 645806 is 608546.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645806.

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 7 ways as a sum of consecutive naturals, for example, 2141 + ... + 2423.

It is an arithmetic number, because the mean of its divisors is an integer number (69864).

2⁶⁴⁵⁸⁰⁶ is an apocalyptic number.

645806 is a deficient number, since it is larger than the sum of its proper divisors (472018).

645806 is a wasteful number, since it uses less digits than its factorization.

645806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 645806 is about 803.6205572283. The cubic root of 645806 is about 86.4372003445.

Subtracting from 645806 its product of nonzero digits (5760), we obtain a palindrome (640046).

The spelling of 645806 in words is "six hundred forty-five thousand, eight hundred six".