645311 has 4 divisors (see below), whose sum is σ = 673392. Its totient is φ = 617232.

The previous prime is 645257. The next prime is 645313. The reversal of 645311 is 113546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 113546 = 2 ⋅56773.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645313) 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 3 ways as a sum of consecutive naturals, for example, 14006 + ... + 14051.

It is an arithmetic number, because the mean of its divisors is an integer number (168348).

2⁶⁴⁵³¹¹ is an apocalyptic number.

645311 is a deficient number, since it is larger than the sum of its proper divisors (28081).

645311 is a wasteful number, since it uses less digits than its factorization.

645311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28080.

The product of its digits is 360, while the sum is 20.

The square root of 645311 is about 803.3125170194. The cubic root of 645311 is about 86.4151104545.

Adding to 645311 its reverse (113546), we get a palindrome (758857).

The spelling of 645311 in words is "six hundred forty-five thousand, three hundred eleven".