The 1st Efreeti, that is all...
Ahirimak is much larger than most Efreeti, he also has green flame that flow around him. Many suspect that he has considerable more power and intelligence that even royal Efreeti.
It is believed that Ahirimak was created by Lucifer to destroy the Djinni, but Ahirimak was uncontrollable so Lucifer sealed him in a lamp of no apparent significance. It is not known if the legend of Djinni being ‘trapped’ in a lamp comes from Lucifer’s actions or it is coincidence.