11811909 has 4 divisors (see below), whose sum is σ = 15749216. Its totient is φ = 7874604.

The previous prime is 11811887. The next prime is 11811913. The reversal of 11811909 is 90911811.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90911811 = 3 ⋅30303937.

It is a de Polignac number, because none of the positive numbers 2^k-11811909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11811929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1968649 + ... + 1968654.

It is an arithmetic number, because the mean of its divisors is an integer number (3937304).

Almost surely, 2^11811909 is an apocalyptic number.

It is an amenable number.

11811909 is a deficient number, since it is larger than the sum of its proper divisors (3937307).

11811909 is an equidigital number, since it uses as much as digits as its factorization.

11811909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3937306.

The product of its (nonzero) digits is 648, while the sum is 30.

The square root of 11811909 is about 3436.8457922927. The cubic root of 11811909 is about 227.7403746811.

It can be divided in two parts, 11811 and 909, that added together give a triangular number (12720 = T₁₅₉).

The spelling of 11811909 in words is "eleven million, eight hundred eleven thousand, nine hundred nine".