31121 has 2 divisors, whose sum is σ = 31122. Its totient is φ = 31120.

The previous prime is 31091. The next prime is 31123. The reversal of 31121 is 12113.

31121 is nontrivially palindromic in base 5.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26896 + 4225 = 164^2 + 65^2 .

It is an emirp because it is prime and its reverse (12113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31121 - 2¹⁰ = 30097 is a prime.

Together with 31123, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31099 and 31108.

It is not a weakly prime, because it can be changed into another prime (31123) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15560 + 15561.

It is an arithmetic number, because the mean of its divisors is an integer number (15561).

2³¹¹²¹ is an apocalyptic number.

It is an amenable number.

31121 is a deficient number, since it is larger than the sum of its proper divisors (1).

31121 is an equidigital number, since it uses as much as digits as its factorization.

31121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6, while the sum is 8.

The square root of 31121 is about 176.4114508755. The cubic root of 31121 is about 31.4546251885.

Adding to 31121 its reverse (12113), we get a palindrome (43234).

It can be divided in two parts, 3112 and 1, that added together give a palindrome (3113).

The spelling of 31121 in words is "thirty-one thousand, one hundred twenty-one".