You really should have multiple input, e.g. one for firstname, middle names, lastname and another one for age. If you want to have some fun though you could try:
>>> input_given="join smith 25"
>>> chars="".join([i for i in input_given if not i.isdigit()])
>>> age=input_given.translate(None,chars)
>>> age
'25'
>>> name=input_given.replace(age,"").strip()
>>> name
'join smith'
This would of course fail if there is multiple numbers in the input. a quick check would be:
assert(age in input_given)
and also:
assert(len(name)<len(input_given))