13231991 has 2 divisors, whose sum is σ = 13231992. Its totient is φ = 13231990.

The previous prime is 13231987. The next prime is 13231997. The reversal of 13231991 is 19913231.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 13231991 - 2² = 13231987 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13231997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6615995 + 6615996.

It is an arithmetic number, because the mean of its divisors is an integer number (6615996).

Almost surely, 2^13231991 is an apocalyptic number.

13231991 is a deficient number, since it is larger than the sum of its proper divisors (1).

13231991 is an equidigital number, since it uses as much as digits as its factorization.

13231991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1458, while the sum is 29.

The square root of 13231991 is about 3637.5803771188. The cubic root of 13231991 is about 236.5239186342.

It can be divided in two parts, 132 and 31991, that added together give a palindrome (32123).

The spelling of 13231991 in words is "thirteen million, two hundred thirty-one thousand, nine hundred ninety-one".