The critical edition of the Mahabharata, compiled by the Bhandarkar Oriental Research Institute (BORI), is collated from 1,259 ancient manuscripts and consists of 18 Parvas and 73,787 verses (excluding the Harivamsa).
The Institute began its project for creating a critical edition on 1 April 1919 and the project was completed on 22 September 1966. The work on Harivamsa took another five years, and was completed in November, 1971. With Harivamsa, the text consists of 79,860 verses. It is said that the original composition of Veda Vyasa contained 100,000 verses.
Here’s the opening mantra of the Mahabharata:
नारायणं नमस्कृत्य नरं चैव नरोत्तमम्
देवीं सरस्वतीं चैव ततो जयम् उदीरयेत्
Om! Having bowed down to Narayana and Nara, the most exalted male being,
and also to the goddess Saraswati, must the word Jaya (victory) be uttered.