Anwar Sadat

... was President of Egypt from 1970 until his death. He also appointed himself as Prime Minister on two occasions: firstly in March 1973, and secondly in May 1980. On the first occasion he served for one day short of six months, and at the time of his assassination he was one year, four months and 22 days into his second term.

So the question is not wrong, but it could be described as confusing because Sadat is much more commonly referred to as the President of Egypt, rather than the Prime Minister.