20439 has 8 divisors (see below), whose sum is σ = 30320. Its totient is φ = 13608.

The previous prime is 20431. The next prime is 20441. The reversal of 20439 is 93402.

20439 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 20439 - 2³ = 20431 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 (20431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 352 + ... + 405.

It is an arithmetic number, because the mean of its divisors is an integer number (3790).

2²⁰⁴³⁹ is an apocalyptic number.

20439 is a deficient number, since it is larger than the sum of its proper divisors (9881).

20439 is an equidigital number, since it uses as much as digits as its factorization.

20439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 766 (or 760 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 20439 is about 142.9650306893. The cubic root of 20439 is about 27.3413453940.

It can be divided in two parts, 204 and 39, that added together give a 5-th power (243 = 3⁵).

The spelling of 20439 in words is "twenty thousand, four hundred thirty-nine".