State: CA - How to best invest in a cash payout from previous employee

I just left my job in June, but before leaving I was paid a nice 6 figure severance package in cash (Living and working in CA). This payment was not for injury reasons, but what kind of tax effect will this cause for me when I file for taxes. New tax bracket even though its a one time payout? How much tax should I expect to have to pay? What ways can I think of investing that payment so that I don't lose too much in taxes? Any advice or suggestions are greatly appreciated.