Its special merits also include the fact that it contains twenty-two letters of the Arabic alphabet, and twenty-two was the number of those who helped the Prophet after he received the revelation.
Seven letters do not occur in al-Fatiha. They are the thā’ of al-thubūr (destruction), the jīm of al-jahīm (Hellfire), the khā’ of al-khawf (fear), the zāy of al-zaqqūm (the tree of bitter fruit in Hell), the shīn of al-Shaqāwa (misfortune) , the zā’ of al-Zulma (darkness)and the fā’ of al-firāq (separation)
If someone firmly believes in (the merit of) this Qur’an chapter and recites it in a state of reverence and veneration, he will be safe from these seven things.
– Shaykh al-Islām Ibrahim Niasse (d.1975) in his Magnum Opus, Kāshif al-Ilbās pg. 183. (Removal of confusion book, available at Wardah Books)