18439 has 2 divisors, whose sum is σ = 18440. Its totient is φ = 18438.

The previous prime is 18433. The next prime is 18443. The reversal of 18439 is 93481.

It is a strong prime.

It is an emirp because it is prime and its reverse (93481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18439 - 2⁷ = 18311 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9219 + 9220.

It is an arithmetic number, because the mean of its divisors is an integer number (9220).

2¹⁸⁴³⁹ is an apocalyptic number.

18439 is a deficient number, since it is larger than the sum of its proper divisors (1).

18439 is an equidigital number, since it uses as much as digits as its factorization.

18439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 25.

The square root of 18439 is about 135.7902794754. The cubic root of 18439 is about 26.4187615336.

The spelling of 18439 in words is "eighteen thousand, four hundred thirty-nine".