I've made a folding test on a note just to see how the numbers fit: I found that the number printed on the front belongs to another note (that one just above that oneon the sheet), so I don't think that the 4th digit partially seen is a "1". Can you post an enlarged scan of the partial serial number? Maybe we can find which number it is...
And there is another note having the rest of the serial AZY3721642 which is somewhere in circulation, whose the serial number at left is missing and a part of the number at right (and maybe completely) missing too.
We can say that this note was on the lower right part of the sheet and a part of the error was trimmed out from the borders of the sheet...
I had reported a partially missing number on a 10$ note last year, for the same reason, but it wasn't so dramatic...
Very nice find..