645765 has 8 divisors (see below), whose sum is σ = 1033248. Its totient is φ = 344400.

The previous prime is 645763. The next prime is 645787. The reversal of 645765 is 567546.

645765 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 645765 - 2¹ = 645763 is a prime.

645765 is a lucky number.

It is a nialpdrome in base 15.

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 645765.

It is not an unprimeable number, because it can be changed into a prime (645763) 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, 21511 + ... + 21540.

It is an arithmetic number, because the mean of its divisors is an integer number (129156).

2⁶⁴⁵⁷⁶⁵ is an apocalyptic number.

It is an amenable number.

645765 is a deficient number, since it is larger than the sum of its proper divisors (387483).

645765 is a wasteful number, since it uses less digits than its factorization.

645765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43059.

The product of its digits is 25200, while the sum is 33.

The square root of 645765 is about 803.5950472719. The cubic root of 645765 is about 86.4353711057.

The spelling of 645765 in words is "six hundred forty-five thousand, seven hundred sixty-five".