The .mobi format is a legacy file type primarily used for older Amazon Kindle devices.
The string is also found in lists of that are or were available for registration.
Shuxiang.org lists "9264.mobi" among thousands of other numeric domains.
There is a coincidental appearance of "9,264" next to the word "Mobile" in historical environmental reports from the EPA . In these tables, it represents a cost figure (in millions of dollars) associated with mobile source pollution, not a specific "mobi" brand or technology.