20839 has 8 divisors (see below), whose sum is σ = 25760. Its totient is φ = 16416.

The previous prime is 20809. The next prime is 20849. The reversal of 20839 is 93802.

20839 = T₅₀ + T₅₁ + ... + T₆₂.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20839 - 2⁵ = 20807 is a prime.

20839 is a lucky number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24 + ... + 205.

It is an arithmetic number, because the mean of its divisors is an integer number (3220).

2²⁰⁸³⁹ is an apocalyptic number.

20839 is a deficient number, since it is larger than the sum of its proper divisors (4921).

20839 is a wasteful number, since it uses less digits than its factorization.

20839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249.

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

The square root of 20839 is about 144.3571958719. The cubic root of 20839 is about 27.5185549708.

The spelling of 20839 in words is "twenty thousand, eight hundred thirty-nine".