11811809 has 4 divisors (see below), whose sum is σ = 11859120. Its totient is φ = 11764500.

The previous prime is 11811797. The next prime is 11811847. The reversal of 11811809 is 90811811.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11811809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11811869) 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 in 3 ways as a sum of consecutive naturals, for example, 23279 + ... + 23780.

It is an arithmetic number, because the mean of its divisors is an integer number (2964780).

Almost surely, 2^11811809 is an apocalyptic number.

It is an amenable number.

11811809 is a deficient number, since it is larger than the sum of its proper divisors (47311).

11811809 is an equidigital number, since it uses as much as digits as its factorization.

11811809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47310.

The product of its (nonzero) digits is 576, while the sum is 29.

The square root of 11811809 is about 3436.8312440386. The cubic root of 11811809 is about 227.7397319935.

The spelling of 11811809 in words is "eleven million, eight hundred eleven thousand, eight hundred nine".