Nc1ccc2c3c1cccc3c(=O)n1c3ccc(Cc4ccc5c(c4)nc4c6ccc(N)c7cccc(c(=O)n54)c76)cc3nc21
A rotatable bond is defined as any single non-ring bond, attached to a non-terminal, non-hydrogen atom. Amide C-N bonds are not counted because of their high barrier to rotation.  How many rotatable bonds does the molecule have?