22181 has 4 divisors (see below), whose sum is σ = 22764. Its totient is φ = 21600.

The previous prime is 22171. The next prime is 22189. The reversal of 22181 is 18122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4225 + 17956 = 65^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 22181 - 2¹⁰ = 21157 is a prime.

It is a super-2 number, since 2×22181² = 983993522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22189) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230 + ... + 311.

It is an arithmetic number, because the mean of its divisors is an integer number (5691).

2²²¹⁸¹ is an apocalyptic number.

It is an amenable number.

22181 is a deficient number, since it is larger than the sum of its proper divisors (583).

22181 is an equidigital number, since it uses as much as digits as its factorization.

22181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582.

The product of its digits is 32, while the sum is 14.

The square root of 22181 is about 148.9328707841. The cubic root of 22181 is about 28.0970273321.

The spelling of 22181 in words is "twenty-two thousand, one hundred eighty-one".