It was my little dream to own 21 BTC and today i achieved it after hard work of so long time.Now i want to make my hard work pay me.I mean,i want that these bitcoins work for me someway and grow.Is there bitcoin bank that pays interest? What will you do with 21 BTC? How will you spend it? How will you grow it? Share anything you want that may help me to decide what should i do. 
I would hold on to them for the future so that I can make more money with Bitcoin, if I would sell them now then I would not make not as much money. I would wait for the price to go up and then sell the 21 Bitcoin.