Search a number
-
+
31391 is a prime number
BaseRepresentation
bin111101010011111
31121001122
413222133
52001031
6401155
7160343
oct75237
947048
1031391
1121648
12161bb
1311399
14b623
15947b
hex7a9f

31391 has 2 divisors, whose sum is σ = 31392. Its totient is φ = 31390.

The previous prime is 31387. The next prime is 31393. The reversal of 31391 is 19313.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31391 - 22 = 31387 is a prime.

Together with 31393, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p3383 and since 31391 and 3383 have the same sum of digits, it is a Honaker prime.

It is a plaindrome in base 13.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 31391.

It is not a weakly prime, because it can be changed into another prime (31393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15695 + 15696.

It is an arithmetic number, because the mean of its divisors is an integer number (15696).

231391 is an apocalyptic number.

31391 is a deficient number, since it is larger than the sum of its proper divisors (1).

31391 is an equidigital number, since it uses as much as digits as its factorization.

31391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81, while the sum is 17.

The square root of 31391 is about 177.1750546776. The cubic root of 31391 is about 31.5453282079.

It can be divided in two parts, 313 and 91, that added together give a palindrome (404).

The spelling of 31391 in words is "thirty-one thousand, three hundred ninety-one".