Number spiral diagonals

Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows:

21 22 23 24 25 20  7  8  9 10 19  6  1  2 11 18  5  4  3 1217 16 15 14 13

It can be verified that the sum of the numbers on the diagonals is 101.

What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way?

Written by gamwe6 who lives and works in San Francisco building useful things. You should follow him on Twitter