Letters of Names of Numbers in Alphabetical Order/French/Historical Note

Theorem
The integers the letters of whose names appear in alphabetical order when written in French was noticed in $1998$ by on reading in  by  ($1997$) that $40$ was the only such number in English.

It is more than probable that others had noticed it before this, but no evidence of this has yet been unearthed.

It crops up online on occasion, for example https://www.mathsisfun.com/puzzles/alphabetical-order-solution.html

The result even appears in contemporary literature: The Curse of the Ice Serpent by Jon Mayhew (2015) features a puzzle whose solution depends on it.