الإجابة

AAWW

No it is not, but it is a highly recommended act of worship with a huge amount of reward  anticipated for those who are involved in such a sort of worship. Nevertheless, memorizing Al-Fatihah is a must because reciting it is one of the pillars of prayers. Also, memorizing some of the short Sorahs is expected from those who follow the Sunnah of the Prophet saaw since reading another Surah after Al-Fatihah is highly preferred.