Zilliogender is a multigender, that is a subset of mathgender, in which one feels as though they have, experience, or encompass a zillion genders. It should be noted that a zillion is not a real number and simply refers to "an indeterminate, very large number", presumably a number larger that a trillion or quadrillion (two of the largest, commonly known numbers) It is similar to billiogender, centilliogender, kilogender, platilligender, and trilligender. It may also be considered a subset to pangender.
History
Zilliogender was coined on July 31, 2018 by Tumblr user arco-pluris.