12399991 has 2 divisors, whose sum is σ = 12399992. Its totient is φ = 12399990.

The previous prime is 12399983. The next prime is 12400001. The reversal of 12399991 is 19999321.

It is a weak prime.

It is an emirp because it is prime and its reverse (19999321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12399991 - 2³ = 12399983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12399901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6199995 + 6199996.

It is an arithmetic number, because the mean of its divisors is an integer number (6199996).

Almost surely, 2^12399991 is an apocalyptic number.

12399991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12399991 is an equidigital number, since it uses as much as digits as its factorization.

12399991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39366, while the sum is 43.

The square root of 12399991 is about 3521.3620944174. The cubic root of 12399991 is about 231.4588494545.

The spelling of 12399991 in words is "twelve million, three hundred ninety-nine thousand, nine hundred ninety-one".