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21839 is a prime number
BaseRepresentation
bin101010101001111
31002221212
411111033
51144324
6245035
7120446
oct52517
932855
1021839
1115454
121077b
139c2c
147d5d
15670e
hex554f

21839 has 2 divisors, whose sum is σ = 21840. Its totient is φ = 21838.

The previous prime is 21821. The next prime is 21841. The reversal of 21839 is 93812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-21839 is a prime.

Together with 21841, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10919 + 10920.

It is an arithmetic number, because the mean of its divisors is an integer number (10920).

221839 is an apocalyptic number.

21839 is a deficient number, since it is larger than the sum of its proper divisors (1).

21839 is an equidigital number, since it uses as much as digits as its factorization.

21839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 23.

The square root of 21839 is about 147.7802422518. The cubic root of 21839 is about 27.9518731084.

The spelling of 21839 in words is "twenty-one thousand, eight hundred thirty-nine".