Question 11520
This is another version of the legend of King Shiram of India who wanted to reward his grand vizier Sissa Ben Dahir for inventing and presenting to him the game of chess.  The clever vizier wanted a grain of wheat on the first square of the chessboard, two grains on the second square, four on the next, and so, doubling the number on each successive square until all of the 64 squares of the chessboard were covered.

Well, this works out to be: {{{2^64 - 1}}} grains of wheat (or rice, in your problem). 

{{{2^64 - 1}}} = 18,446,744,073,709,551,615 grains of rice.

The volume of rice? How do you tell?  5,000,000 grains of rice in a bushel?

Around 400 billion bushels of rice!