This achievement it's stackable you don't need to manage the 11,240 at the same time.
If you want to get easy pixels you can do it in the world 2 level 2 (2:2) At the beginning of the level there are one chest and five wasps. If you buy the upgrade (MIDAS) kill the last wasp and enter the next room, come back and kill the wasp again, enter the next room. (keep doing until you get the amount you need)
Hope this help.