[jasode]

Depending on the word, The centi- prefix can mean multiply by 100 instead of divide by 100.

The popularity of "centimillionaire" to mean $100 million is reflected in Google's top results.[1] Merriam-Webster dictionary, Wikipedia, and Forbes all mention centimillionaire as $100 million.

Likewise, "centipede" means a creature with ~100 feet (even though no species actually has exactly 100 feet).

Language usage is ultimately dictated by popularity instead of "correct" scientific prefix rules and it looks like "hectamillionaire" is not the widespread choice to label 10^8 dollars.[2]

[1] 18000 results for "centimillionaire": https://www.google.com/search?q=centimillionaire

[2] only 1880 results for "hectamillionaire": "https://www.google.com/search?q=hectamillionaire