If there isn't a space following a prefix function, Maxima
invents one:
(%i1) prefix("div", 142, expr,expr);
(%o1) DIV
(%i2) divprod(a,b);
Wrong no. of args to product
-- an error. Quitting. To debug this try DEBUGMODE(TRUE);
So this would seem to be a bug in the parser.
Barton