To calculate this is very simple, but not necessarily easy. If you have an investment the pays x% per year, over the ammount invested, you will need to do:
10080/x% = C
When C is the Capital invested. As you must've realized the bigger x is, smaller is the ammount of capital invested. If you have a 2% per annum interest , you would need to invest:
10080/x% = 504000
Please consider that I'm not taking into account inflation, taxes and fees since they are very country-specific.