One other observation, 72 is the number of divisions in the zodiac, and the number of angels in the Shemhamephorash. When you add 1 to a special number, it either means a victory, conquering, overcoming of the previous number. Likewise adding 1 to create a special number is considered the completion or attainment by adding the missing monad.

71 is a very special number, worthy of its own thread. In general it represents the way, and its reflex 17 is ZAIN, or Z-AIN - by Qabalah the strong interpretation is of the serpent vibrating in the void. It also refers to a Masonic attribute relating to Hiram. But anyway, adding 2 to 71 implies extension of the way beyond the shackles of YHVY (72) and becoming the 'Lord of the Aeon of the Serpent Between the Neither-Neither' as 73.