12657991 has 2 divisors, whose sum is σ = 12657992. Its totient is φ = 12657990.

The previous prime is 12657977. The next prime is 12658031. The reversal of 12657991 is 19975621.

It is an a-pointer prime, because the next prime (12658031) can be obtained adding 12657991 to its sum of digits (40).

It is a weak prime.

It is an emirp because it is prime and its reverse (19975621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12657991 - 2⁷ = 12657863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12657901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6328995 + 6328996.

It is an arithmetic number, because the mean of its divisors is an integer number (6328996).

Almost surely, 2^12657991 is an apocalyptic number.

12657991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12657991 is an equidigital number, since it uses as much as digits as its factorization.

12657991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34020, while the sum is 40.

The square root of 12657991 is about 3557.8070492931. The cubic root of 12657991 is about 233.0531232675.

The spelling of 12657991 in words is "twelve million, six hundred fifty-seven thousand, nine hundred ninety-one".