You can make quite a few dictionary recognized words from the letters in "sixteen". Some examples are tense, teens, inset, exist, exits, tins, ties, seen, sent, next, exit, and nest.
You can make at least sixteen words.
Sixteen hundredths.
Sixteen sixteenths make a whole (1).
one
4 qts
Sixteen
five hundred sixteen or five hundred and sixteen
24 42
Sixteen.
16 in number words = sixteen
Sixteen times to do it
As separate words, it is plural.We just finished sixteen hours on the job.As a compound adjective, it is singularWe just finished a sixteen-hour shift.