21843 has 8 divisors (see below), whose sum is σ = 32400. Its totient is φ = 14544.

The previous prime is 21841. The next prime is 21851. The reversal of 21843 is 34812.

It is a happy number.

It is not a de Polignac number, because 21843 - 2¹ = 21841 is a prime.

It is a nialpdrome in base 16.

It is a zygodrome in base 5.

It is not an unprimeable number, because it can be changed into a prime (21841) 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, 378 + ... + 431.

It is an arithmetic number, because the mean of its divisors is an integer number (4050).

21843 is a Friedman number, since it can be written as (4^8-1)/3-2, using all its digits and the basic arithmetic operations.

2²¹⁸⁴³ is an apocalyptic number.

21843 is a deficient number, since it is larger than the sum of its proper divisors (10557).

21843 is an equidigital number, since it uses as much as digits as its factorization.

21843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 818 (or 812 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 21843 is about 147.7937752410. The cubic root of 21843 is about 27.9535795459.

It can be divided in two parts, 2184 and 3, that added together give a 7-th power (2187 = 3⁷).

The spelling of 21843 in words is "twenty-one thousand, eight hundred forty-three".