31138381 has 2 divisors, whose sum is σ = 31138382. Its totient is φ = 31138380.

The previous prime is 31138313. The next prime is 31138417. The reversal of 31138381 is 18383113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27562500 + 3575881 = 5250^2 + 1891^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31138381 is a prime.

It is a super-2 number, since 2×31138381² = 1939197542602322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31138301) 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, 15569190 + 15569191.

It is an arithmetic number, because the mean of its divisors is an integer number (15569191).

Almost surely, 2^31138381 is an apocalyptic number.

It is an amenable number.

31138381 is a deficient number, since it is larger than the sum of its proper divisors (1).

31138381 is an equidigital number, since it uses as much as digits as its factorization.

31138381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 28.

The square root of 31138381 is about 5580.1775061372. The cubic root of 31138381 is about 314.6047987497.

It can be divided in two parts, 3 and 1138381, that multiplied together give a palindrome (3415143).

The spelling of 31138381 in words is "thirty-one million, one hundred thirty-eight thousand, three hundred eighty-one".