11509 has 4 divisors (see below), whose sum is σ = 12204. Its totient is φ = 10816.

The previous prime is 11503. The next prime is 11519. The reversal of 11509 is 90511.

11509 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10609 + 900 = 103^2 + 30^2 .

It is a cyclic number.

It is not a de Polignac number, because 11509 - 2¹¹ = 9461 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11492 and 11501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 322 + ... + 355.

It is an arithmetic number, because the mean of its divisors is an integer number (3051).

2¹¹⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

11509 is a deficient number, since it is larger than the sum of its proper divisors (695).

11509 is an equidigital number, since it uses as much as digits as its factorization.

11509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 694.

The product of its (nonzero) digits is 45, while the sum is 16.

The square root of 11509 is about 107.2800074571. The cubic root of 11509 is about 22.5776739343.

The spelling of 11509 in words is "eleven thousand, five hundred nine".