840439 has 2 divisors, whose sum is σ = 840440. Its totient is φ = 840438.

The previous prime is 840353. The next prime is 840451. The reversal of 840439 is 934048.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 840439 - 2¹¹ = 838391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840479) 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, 420219 + 420220.

It is an arithmetic number, because the mean of its divisors is an integer number (420220).

2⁸⁴⁰⁴³⁹ is an apocalyptic number.

840439 is a deficient number, since it is larger than the sum of its proper divisors (1).

840439 is an equidigital number, since it uses as much as digits as its factorization.

840439 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 840439 is about 916.7546018428. The cubic root of 840439 is about 94.3703137886.

The spelling of 840439 in words is "eight hundred forty thousand, four hundred thirty-nine".