How many letters does the top answer for “an illiterate person who does not know the alphabet” have?

The most common answer is analphabet (10 letters).

Crossword clue: an illiterate person who does not know the alphabet

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

analphabet 10 letters wn-def

an illiterate person who does not know the alphabet

analphabetic 12 letters wn-def

an illiterate person who does not know the alphabet