O=C(CC[N+](=O)[O-])OCC1OC(O)C(OC(=O)CC[N+](=O)[O-])[C@@H](OC(=O)CC[N+](=O)[O-])C1OC(=O)CC[N+](=O)[O-]
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?