20389 has 2 divisors, whose sum is σ = 20390. Its totient is φ = 20388.

The previous prime is 20369. The next prime is 20393. The reversal of 20389 is 98302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20164 + 225 = 142^2 + 15^2 .

It is a cyclic number.

It is not a de Polignac number, because 20389 - 2⁵ = 20357 is a prime.

It is a super-2 number, since 2×20389² = 831422642, which contains 22 as substring.

It is an Ulam number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10194 + 10195.

It is an arithmetic number, because the mean of its divisors is an integer number (10195).

2²⁰³⁸⁹ is an apocalyptic number.

It is an amenable number.

20389 is a deficient number, since it is larger than the sum of its proper divisors (1).

20389 is an equidigital number, since it uses as much as digits as its factorization.

20389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 20389 is about 142.7900556762. The cubic root of 20389 is about 27.3190321115.

It can be divided in two parts, 203 and 89, that added together give a palindrome (292).

The spelling of 20389 in words is "twenty thousand, three hundred eighty-nine".