20005439 has 2 divisors, whose sum is σ = 20005440. Its totient is φ = 20005438.

The previous prime is 20005429. The next prime is 20005441. The reversal of 20005439 is 93450002.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20005439 - 2²⁰ = 18956863 is a prime.

Together with 20005441, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1270931 and since 20005439 and 1270931 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20005429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10002719 + 10002720.

It is an arithmetic number, because the mean of its divisors is an integer number (10002720).

Almost surely, 2^20005439 is an apocalyptic number.

20005439 is a deficient number, since it is larger than the sum of its proper divisors (1).

20005439 is an equidigital number, since it uses as much as digits as its factorization.

20005439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 20005439 is about 4472.7440123486. The cubic root of 20005439 is about 271.4663656250.

The spelling of 20005439 in words is "twenty million, five thousand, four hundred thirty-nine".