231231391 has 2 divisors, whose sum is σ = 231231392. Its totient is φ = 231231390.

The previous prime is 231231367. The next prime is 231231409. The reversal of 231231391 is 193132132.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231231391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231231191) 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, 115615695 + 115615696.

It is an arithmetic number, because the mean of its divisors is an integer number (115615696).

Almost surely, 2^231231391 is an apocalyptic number.

231231391 is a deficient number, since it is larger than the sum of its proper divisors (1).

231231391 is an equidigital number, since it uses as much as digits as its factorization.

231231391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 25.

The square root of 231231391 is about 15206.2944532848. The cubic root of 231231391 is about 613.7840482022.

The spelling of 231231391 in words is "two hundred thirty-one million, two hundred thirty-one thousand, three hundred ninety-one".