645439 has 4 divisors (see below), whose sum is σ = 683424. Its totient is φ = 607456.

The previous prime is 645433. The next prime is 645443. The reversal of 645439 is 934546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645439 - 2³ = 645431 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645439.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645431) 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, 18967 + ... + 19000.

It is an arithmetic number, because the mean of its divisors is an integer number (170856).

2⁶⁴⁵⁴³⁹ is an apocalyptic number.

645439 is a deficient number, since it is larger than the sum of its proper divisors (37985).

645439 is a wasteful number, since it uses less digits than its factorization.

645439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37984.

The product of its digits is 12960, while the sum is 31.

The square root of 645439 is about 803.3921831833. The cubic root of 645439 is about 86.4208236702.

The spelling of 645439 in words is "six hundred forty-five thousand, four hundred thirty-nine".