31231 has 2 divisors, whose sum is σ = 31232.
Its totient is φ = 31230.
The previous prime is 31223. The next prime is 31237. The reversal of 31231 is 13213.
Subtracting from 31231 its product of digits (18), we obtain a palindrome (31213).
Adding to 31231 its reverse (13213), we get a palindrome (44444).
It can be divided in two parts, 312 and 31, that added together give a palindrome (343).
31231 is nontrivially palindromic in base 11.
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 31231 - 23 = 31223 is a prime.
It is a super-2 number, since 2×312312 = 1950750722, which contains 22 as substring.
31231 is a lucky number.
It is a plaindrome in base 16.
It is a zygodrome in base 2.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (31237) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15615 + 15616.
It is an arithmetic number, because the mean of its divisors is an integer number (15616).
231231 is an apocalyptic number.
31231 is a deficient number, since it is larger than the sum of its proper divisors (1).
31231 is an equidigital number, since it uses as much as digits as its factorization.
31231 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 18, while the sum is 10.
The square root of 31231 is about 176.7229470103.
The cubic root of 31231 is about 31.4916413532.
The spelling of 31231 in words is "thirty-one thousand, two hundred thirty-one".