12891209 has 2 divisors, whose sum is σ = 12891210. Its totient is φ = 12891208.

The previous prime is 12891187. The next prime is 12891211. The reversal of 12891209 is 90219821.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6996025 + 5895184 = 2645^2 + 2428^2 .

It is a cyclic number.

It is not a de Polignac number, because 12891209 - 2¹² = 12887113 is a prime.

Together with 12891211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12891259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6445604 + 6445605.

It is an arithmetic number, because the mean of its divisors is an integer number (6445605).

Almost surely, 2^12891209 is an apocalyptic number.

It is an amenable number.

12891209 is a deficient number, since it is larger than the sum of its proper divisors (1).

12891209 is an equidigital number, since it uses as much as digits as its factorization.

12891209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 12891209 is about 3590.4329822460. The cubic root of 12891209 is about 234.4757227289.

The spelling of 12891209 in words is "twelve million, eight hundred ninety-one thousand, two hundred nine".