illiteracy

I have read many articles on Prophet Muhammad (pbuh) and the number of his wives differs. The number eleven (11) doesn't include Mariya al-Qibtiya, known as Mary the Copt. I would like to know more about this. Some Orientalists said that Prophet Muhammad (pbuh) was literate. They've mentioned two examples: The Treaty of Hudaibiah and two versions I've read: A. The prophet signed “son of Abdullah” B. The prophet omitted the word “apostle of God” Another story is that at his death bed, the prophet asked for a pen and ink to write who was to be his successor. Hope to hear from you soon. Thank you, wa-salaam. P.S.: Glad 'Ask About Islam' is available :)