To classify as a novel, a piece of prose has to be at least 100 pages in length. Those books having shorter lengths are called novellas. The content can draw on real life incidents, but a novel never claims to have real characters and the facts mentioned in a novel cannot be verified in real life.
There are many characters in a novel and the story also has many twists with events and incidents taking place in the lives of the main characters that are linked with each other. There are sub stories and sub plots running in parallel to the main story which is the beauty of a novel. There are many genres in which novels are written, and the word count for all genres is different for a book to be called a novel. However, in general, the minimum word count for a book to be labeled as a novel is 40000.