13191991 has 2 divisors, whose sum is σ = 13191992. Its totient is φ = 13191990.

The previous prime is 13191979. The next prime is 13192001. The reversal of 13191991 is 19919131.

It is a strong prime.

It is an emirp because it is prime and its reverse (19919131) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13191991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13191901) 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, 6595995 + 6595996.

It is an arithmetic number, because the mean of its divisors is an integer number (6595996).

Almost surely, 2^13191991 is an apocalyptic number.

13191991 is a deficient number, since it is larger than the sum of its proper divisors (1).

13191991 is an equidigital number, since it uses as much as digits as its factorization.

13191991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2187, while the sum is 34.

The square root of 13191991 is about 3632.0780553287. The cubic root of 13191991 is about 236.2853426405.

The spelling of 13191991 in words is "thirteen million, one hundred ninety-one thousand, nine hundred ninety-one".