12009 has 4 divisors (see below), whose sum is σ = 16016. Its totient is φ = 8004.

The previous prime is 12007. The next prime is 12011. The reversal of 12009 is 90021.

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.

It is an interprime number because it is at equal distance from previous prime (12007) and next prime (12011).

It is not a de Polignac number, because 12009 - 2¹ = 12007 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 11985 and 12003.

It is not an unprimeable number, because it can be changed into a prime (12007) 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, 1999 + ... + 2004.

It is an arithmetic number, because the mean of its divisors is an integer number (4004).

2¹²⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

12009 is a deficient number, since it is larger than the sum of its proper divisors (4007).

12009 is an equidigital number, since it uses as much as digits as its factorization.

12009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4006.

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 12009 is about 109.5855829934. The cubic root of 12009 is about 22.9000069920.

Adding to 12009 its sum of digits (12), we get a palindrome (12021).

The spelling of 12009 in words is "twelve thousand, nine".