12181 has 4 divisors (see below), whose sum is σ = 13132. Its totient is φ = 11232.

The previous prime is 12163. The next prime is 12197. The reversal of 12181 is 18121.

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 1156 + 11025 = 34^2 + 105^2 .

It is not a de Polignac number, because 12181 - 2⁵ = 12149 is a prime.

It is a super-2 number, since 2×12181² = 296753522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 937 = 12181 / (1 + 2 + 1 + 8 + 1).

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12101) 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, 456 + ... + 481.

It is an arithmetic number, because the mean of its divisors is an integer number (3283).

2¹²¹⁸¹ is an apocalyptic number.

It is an amenable number.

12181 is a deficient number, since it is larger than the sum of its proper divisors (951).

12181 is an equidigital number, since it uses as much as digits as its factorization.

12181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 950.

The product of its digits is 16, while the sum is 13.

The square root of 12181 is about 110.3675676999. The cubic root of 12181 is about 23.0088182947.

It can be divided in two parts, 121 and 81, that multiplied together give a square (9801 = 99²).

The spelling of 12181 in words is "twelve thousand, one hundred eighty-one".