11911809 has 16 divisors (see below), whose sum is σ = 19548032. Its totient is φ = 6283008.

The previous prime is 11911807. The next prime is 11911811. The reversal of 11911809 is 90811911.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (11911807) and next prime (11911811).

It is not a de Polignac number, because 11911809 - 2¹ = 11911807 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (11911807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21544 + ... + 22089.

It is an arithmetic number, because the mean of its divisors is an integer number (1221752).

Almost surely, 2^11911809 is an apocalyptic number.

It is an amenable number.

11911809 is a deficient number, since it is larger than the sum of its proper divisors (7636223).

11911809 is a wasteful number, since it uses less digits than its factorization.

11911809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43656.

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

The square root of 11911809 is about 3451.3488667476. The cubic root of 11911809 is about 228.3806161812.

It can be divided in two parts, 11911 and 809, that added together give a triangular number (12720 = T₁₅₉).

The spelling of 11911809 in words is "eleven million, nine hundred eleven thousand, eight hundred nine".