I tried to find a lisp function to convert between numbers and strings and after a little googling I fond a function with the same name. when I entered (itoa 1)
SLI
FYI: I believe (itoa #) is only a function in AutoLISP - the LISP variant embedded in AutoCAD drafting software. AutoLISP has far fewer functions than Common Lisp and sometimes identical functions with a different name or functions with the same name that operate differently.
That's probably why it didn't work for you. I use AutoLISP regularly and (itoa #) would do exactly what you want there.