36-bit was a common enough word length. Not just UNIVAC, but IBM 360, PDP-6/PDP-10, and some others. Convenient both for octal (multiple of 3 bits) and working with pre-ASCII, 6-bit character encodings (multiple of 6 bits).
Which is why we have UTF-9 and UTF-18, as defined in RFC 4042.
I was coming to mention this, though I think my memory goes back to some LISP machine (and was related to car/cdr and related encoding if I'm not mistaken)
They are pretty impressive machines. The loadable microcode store is especially interesting, they allow you to emulate an arbitary CPU. Diagnostics in 'IBM' mode was a real possibility on these!
Had a 36 bit word length resulting in a 9 bit 'byte'.