645875 has 8 divisors (see below), whose sum is σ = 806208. Its totient is φ = 516600.

The previous prime is 645857. The next prime is 645877. The reversal of 645875 is 578546.

It is not a de Polignac number, because 645875 - 2¹⁴ = 629491 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645875.

It is not an unprimeable number, because it can be changed into a prime (645877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2459 + ... + 2708.

It is an arithmetic number, because the mean of its divisors is an integer number (100776).

2⁶⁴⁵⁸⁷⁵ is an apocalyptic number.

645875 is a deficient number, since it is larger than the sum of its proper divisors (160333).

645875 is an equidigital number, since it uses as much as digits as its factorization.

645875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5182 (or 5172 counting only the distinct ones).

The product of its digits is 33600, while the sum is 35.

The square root of 645875 is about 803.6634867903. The cubic root of 645875 is about 86.4402786448.

The spelling of 645875 in words is "six hundred forty-five thousand, eight hundred seventy-five".