I don't have the exact number off the top of my head. But a quick search on manga forums or asking fellow manga enthusiasts might help you get the answer you're looking for.
The 'Maximum Ride' series already has a unique blend of science - fiction and adventure. 'Maximum Ride Angel' could bring in a spiritual or otherworldly element with the focus on angels. This addition of the angel concept can make it stand out as it may introduce different kinds of conflicts and relationships compared to the previous books in the series. For example, the angels could bring new moral dilemmas or new allies/ enemies for the main characters.
It's a part of the 'Maximum Ride' series. The 'Maximum Ride' novels are quite popular, especially among young adult readers. They often feature characters with special abilities. In this novel, it likely delves deeper into the angel - related aspects within the 'Maximum Ride' universe, with exciting adventures and character developments.
I'm not sure exactly, but there are quite a few. You might want to check the official publisher's website or related comic databases for the accurate count.