12109991 has 2 divisors, whose sum is σ = 12109992. Its totient is φ = 12109990.

The previous prime is 12109987. The next prime is 12110003. The reversal of 12109991 is 19990121.

12109991 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 12109991 - 2² = 12109987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12109901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6054995 + 6054996.

It is an arithmetic number, because the mean of its divisors is an integer number (6054996).

Almost surely, 2^12109991 is an apocalyptic number.

12109991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12109991 is an equidigital number, since it uses as much as digits as its factorization.

12109991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 12109991 is about 3479.9412351360. The cubic root of 12109991 is about 229.6402125276.

The spelling of 12109991 in words is "twelve million, one hundred nine thousand, nine hundred ninety-one".