11951809 has 2 divisors, whose sum is σ = 11951810. Its totient is φ = 11951808.

The previous prime is 11951803. The next prime is 11951813. The reversal of 11951809 is 90815911.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10870209 + 1081600 = 3297^2 + 1040^2 .

It is an emirp because it is prime and its reverse (90815911) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11951809 is a prime.

It is not a weakly prime, because it can be changed into another prime (11951803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5975904 + 5975905.

It is an arithmetic number, because the mean of its divisors is an integer number (5975905).

Almost surely, 2^11951809 is an apocalyptic number.

It is an amenable number.

11951809 is a deficient number, since it is larger than the sum of its proper divisors (1).

11951809 is an equidigital number, since it uses as much as digits as its factorization.

11951809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 34.

The square root of 11951809 is about 3457.1388459245. The cubic root of 11951809 is about 228.6359655375.

The spelling of 11951809 in words is "eleven million, nine hundred fifty-one thousand, eight hundred nine".