The number 9 is the natural number following 8 and preceding 10. It is significant in various contexts, including mathematics, history, and culture. Mathematically, 9 is the fourth composite number, the first odd composite number, and the largest single-digit number in the decimal system. In arithmetic, 9 holds unique properties such as being the only square number that is the sum of two consecutive cubes (32=9=13+233^2=9=1^3+2^332=9=13+23) and is involved in concepts like casting out nines, a method to check calculations. The digit 9 evolved from ancient Indian numerals and has a shape resembling an inverted 6 in modern typefaces, with distinct variants for clarity in different contexts.

Additionally, "9" is also known as a 2009 animated post-apocalyptic science fiction film directed by Shane Acker, telling the story of rag doll-like creatures in a devastated world after humans have been destroyed by war machines. The film explores themes of survival, artificial life, and sacrifice and features voice work by Elijah Wood among others. It was produced by Tim Burton and others, and combines thrilling visuals with deep storytelling.

In summary, "9" can refer both to the numerical digit with its rich mathematical and historical background and to the animated film with post- apocalyptic themes, depending on the context of your inquiry.