Eh? No, that was only slightly related to the OP.
But really, whenever I have to look for significance in the numbers, it never ends well.
Well in all honesty the chance of it being an oversight is big. It wouldn't be the first one in the SI books. Take for example the http://www.uesp.net/wiki/Shivering:Myths_of_Sheogorath.
In "Sheogorath and King Lyandir" part, Sheogorath appears to the king in his dreams citing:
"Sheogorath heard their pleas and decided to visit King Lyandir. He appeared to the king in his dreams as a field of flowers, each with arms instead of petals and the face of the Madgod in the center."
However in the same book, in the chapter "The Contest of Wills" it is stated citing:
"He hadn't slept for fear of Sheogorath invading his dreams. (Which was foolish, as dreams are the domain of Vaermina, may She grant us Restful Sleep.)"
A better contradiction couldn't be found. So perhaps the author of XVI accords just didn't count things right, and mechanically assigned the magical known number of Princes to the title.