31081 has 2 divisors, whose sum is σ = 31082. Its totient is φ = 31080.

The previous prime is 31079. The next prime is 31091. The reversal of 31081 is 18013.

31081 is nontrivially palindromic in base 9.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24025 + 7056 = 155^2 + 84^2 .

It is an emirp because it is prime and its reverse (18013) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31081 - 2¹ = 31079 is a prime.

It is a super-2 number, since 2×31081² = 1932057122, which contains 22 as substring.

Together with 31079, it forms a pair of twin primes.

31081 is a lucky number.

It is a plaindrome in base 13.

It is a nialpdrome in base 15.

It is a zygodrome in base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15540 + 15541.

It is an arithmetic number, because the mean of its divisors is an integer number (15541).

2³¹⁰⁸¹ is an apocalyptic number.

31081 is the 112-nd centered pentagonal number.

It is an amenable number.

31081 is a deficient number, since it is larger than the sum of its proper divisors (1).

31081 is an equidigital number, since it uses as much as digits as its factorization.

31081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 31081 is about 176.2980430975. The cubic root of 31081 is about 31.4411431405.

Adding to 31081 its reverse (18013), we get a palindrome (49094).

The spelling of 31081 in words is "thirty-one thousand, eighty-one".