645855 has 16 divisors (see below), whose sum is σ = 1181184. Its totient is φ = 295200.

The previous prime is 645851. The next prime is 645857. The reversal of 645855 is 558546.

It is not a de Polignac number, because 645855 - 2² = 645851 is a prime.

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 645855.

It is not an unprimeable number, because it can be changed into a prime (645851) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2971 + ... + 3180.

It is an arithmetic number, because the mean of its divisors is an integer number (73824).

2⁶⁴⁵⁸⁵⁵ is an apocalyptic number.

645855 is a deficient number, since it is larger than the sum of its proper divisors (535329).

645855 is a wasteful number, since it uses less digits than its factorization.

645855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6166.

The product of its digits is 24000, while the sum is 33.

The square root of 645855 is about 803.6510436751. The cubic root of 645855 is about 86.4393864064.

The spelling of 645855 in words is "six hundred forty-five thousand, eight hundred fifty-five".