13811209 has 2 divisors, whose sum is σ = 13811210. Its totient is φ = 13811208.

The previous prime is 13811207. The next prime is 13811227. The reversal of 13811209 is 90211831.

13811209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8065600 + 5745609 = 2840^2 + 2397^2 .

It is an emirp because it is prime and its reverse (90211831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13811209 - 2¹ = 13811207 is a prime.

Together with 13811207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (13811207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6905604 + 6905605.

It is an arithmetic number, because the mean of its divisors is an integer number (6905605).

Almost surely, 2^13811209 is an apocalyptic number.

It is an amenable number.

13811209 is a deficient number, since it is larger than the sum of its proper divisors (1).

13811209 is an equidigital number, since it uses as much as digits as its factorization.

13811209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 13811209 is about 3716.3434986556. The cubic root of 13811209 is about 239.9259551673.

The spelling of 13811209 in words is "thirteen million, eight hundred eleven thousand, two hundred nine".