As usual, there's more than one way to do it, to improve readability of numbers that is. For display purposes, the old comma as a thousands separator works for numbers in millions range. You can also help the eyes by using a non-lining figures font, if available. For very large figures it's usually useful to have some other number as a comparison, and therefore lends itself to a graph or other order of difference comparison device. By the way the number in the example (1048576) is not exactly 1.05e6, if accuracy mattered; or otherwise just say 1mil.