Are there obligatory prostrations in the Qur'an, apart from the other prostrations, or are they all the same, and is what is said about the prostrations in Surat Fussilat, Al-'Alaq, An-Najm, and As-Sajdah being obligatory prostrations correct?

There are fourteen prostrations of recitation in the Holy Quran: in Al-A'raf, Ar-Ra'd, An-Nahl, Al-Isra, Maryam, two prostrations in Al-Hajj, and in Al-Furqan, An-Naml, Alif Lam Mim Tanzil, Ha Mim As-Sajdah, and three in Al-Mufassal: An-Najm, Al-Inshiqaq, and Iqra' Bismi Rabbik. These prostrations are recommended, not obligatory.