21889 has 8 divisors (see below), whose sum is σ = 25920. Its totient is φ = 18096.

The previous prime is 21881. The next prime is 21893. The reversal of 21889 is 98812.

21889 is nontrivially palindromic in base 12.

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 21889 - 2³ = 21881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21881) 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, 342 + ... + 400.

It is an arithmetic number, because the mean of its divisors is an integer number (3240).

2²¹⁸⁸⁹ is an apocalyptic number.

It is an amenable number.

21889 is a deficient number, since it is larger than the sum of its proper divisors (4031).

21889 is an equidigital number, since it uses as much as digits as its factorization.

21889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119.

The product of its digits is 1152, while the sum is 28.

The square root of 21889 is about 147.9493156456. The cubic root of 21889 is about 27.9731886207.

It can be divided in two parts, 2188 and 9, that added together give a cube (2197 = 13³).

The spelling of 21889 in words is "twenty-one thousand, eight hundred eighty-nine".