20844 has 24 divisors (see below), whose sum is σ = 54320. Its totient is φ = 6912.

The previous prime is 20809. The next prime is 20849. The reversal of 20844 is 44802.

It is a happy number.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20844.

It is not an unprimeable number, because it can be changed into a prime (20849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12 + ... + 204.

2²⁰⁸⁴⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20844, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27160).

20844 is an abundant number, since it is smaller than the sum of its proper divisors (33476).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20844 is a wasteful number, since it uses less digits than its factorization.

20844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206 (or 198 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 20844 is about 144.3745129862. The cubic root of 20844 is about 27.5207556805.

It can be divided in two parts, 208 and 44, that added together give a palindrome (252).

The spelling of 20844 in words is "twenty thousand, eight hundred forty-four".