פ \ ף Pe, the 17th letter, Gematria 80
פ is the 4th letter of the set of 5 that has a different final form ף, and it is also part of the BegadKepahat group of letters that have a secondary pronunciation. The secondary pronunciation of P is F, in both Modern Hebrew and Aramaic.
Like with Abraham/Avraham in the case of ב (Bet), one could find Semitic words imported into other languages spelled with either P or F, because the consonant is פ but the pronunciation is F. E.g. Yosep/Yosef.
The word for Mouth in Modern Hebrew is פה (Pe). Fancy that one too.