645839 has 2 divisors, whose sum is σ = 645840. Its totient is φ = 645838.

The previous prime is 645833. The next prime is 645851. The reversal of 645839 is 938546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645839 - 2⁸ = 645583 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 645799 and 645808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645833) 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 as a sum of consecutive naturals, namely, 322919 + 322920.

It is an arithmetic number, because the mean of its divisors is an integer number (322920).

2⁶⁴⁵⁸³⁹ is an apocalyptic number.

645839 is a deficient number, since it is larger than the sum of its proper divisors (1).

645839 is an equidigital number, since it uses as much as digits as its factorization.

645839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 35.

The square root of 645839 is about 803.6410890441. The cubic root of 645839 is about 86.4386726024.

The spelling of 645839 in words is "six hundred forty-five thousand, eight hundred thirty-nine".