How many unmarried daughters who prophesied did Philip the evangelist have?

Answer: Four

In Caesarea Paul stayed with Philip the evangelist, one of the Seven, who had four unmarried daughters who prophesied.

“Leaving the next day, we went on to Caesarea and stayed at the home of Philip the evangelist, who was one of the Seven. He had four unmarried daughters who prophesied.”— Acts 21:8-9 (BSB)