Can't have identifiers in Flex starting with numbers, so you'll have to change your data.
I figured as much, only issue is this is the native format for getting results from Drupal, not too easy to change the core data. Oh well....
Well, you might be able to iterate over the data in a for...in loop, and use obj[key] syntax or just use a for each...in loop, where you don't even deal with the keys, and stuff the data in a Flex structure of some sort. Not easy, but perhaps doable? You need to play with this a bit.
Otherwise deal with repackaging the data on the server side.
Objects in ActionScript can have dynamic properties at runtime that have numeric names. (Previous responders are thinking about compile-time properties, which can't have such a name.) And instead of obj.foo you can write obj["foo"].
So, if you have obj:Object, then when you write either obj or obj["212"] you are accessing a property whose name is the string "212". So you should be able to use binding.name or binding["212"].name to get what you want.
Adobe Flex SDK Team