18131 has 2 divisors, whose sum is σ = 18132. Its totient is φ = 18130.
The previous prime is 18127. The next prime is 18133. The reversal of 18131 is 13181.
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 18131 - 22 = 18127 is a prime.
It is a super-2 number, since 2×181312 = 657466322, which contains 22 as substring.
It is a Sophie Germain prime.
Together with 18133, it forms a pair of twin primes.
It is a Chen prime.
It is a plaindrome in base 15.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 18131.
It is not a weakly prime, because it can be changed into another prime (18133) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9065 + 9066.
It is an arithmetic number, because the mean of its divisors is an integer number (9066).
18131 is a deficient number, since it is larger than the sum of its proper divisors (1).
18131 is an equidigital number, since it uses as much as digits as its factorization.
18131 is an evil number, because the sum of its binary digits is even.
The product of its digits is 24, while the sum is 14.
The square root of 18131 is about 134.6514017751. The cubic root of 18131 is about 26.2708375739.
Adding to 18131 its sum of digits (14), we get a triangular number (18145 = T190).
Subtracting from 18131 its reverse (13181), we obtain a triangular number (4950 = T99).
It can be divided in two parts, 181 and 31, that added together give a palindrome (212).
The spelling of 18131 in words is "eighteen thousand, one hundred thirty-one".
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