31122391 has 2 divisors, whose sum is σ = 31122392. Its totient is φ = 31122390.

The previous prime is 31122373. The next prime is 31122401. The reversal of 31122391 is 19322113.

It is a strong prime.

It is an emirp because it is prime and its reverse (19322113) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31122391 is a prime.

It is equal to p_1923007 and since 31122391 and 1923007 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31122331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561195 + 15561196.

It is an arithmetic number, because the mean of its divisors is an integer number (15561196).

Almost surely, 2^31122391 is an apocalyptic number.

31122391 is a deficient number, since it is larger than the sum of its proper divisors (1).

31122391 is an equidigital number, since it uses as much as digits as its factorization.

31122391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 22.

The square root of 31122391 is about 5578.7445720341. The cubic root of 31122391 is about 314.5509381881.

It can be divided in two parts, 31122 and 391, that added together give a palindrome (31513).

The spelling of 31122391 in words is "thirty-one million, one hundred twenty-two thousand, three hundred ninety-one".