Investing is the best way to go about utilizing 21+ BTC. only to increase riches further.
I would do 2 investments with this amount of bitcoin and I hope someone is going to give me this amount of bitcoins at all. I would probably invest with trading and going to allocate maybe 5 bitcoins to it and for the other investments I am going to invest 6 bitcoins and going to sell it to fiat and build my real business in real world. And going to hold 10 bitcoins.