This is the 13226th most frequent Russian word.
многомиллионные
"Многомиллионные" means "multimillion" or "many millions."
In this sentence, "многомиллионные" modifies "успехи" (successes) and conveys the idea that the successes are valued in the range of millions, emphasizing their large scale or financial magnitude.
Многомиллионные успехи компании впечатляют.
The multi-million successes of the company are impressive.
Here, "многомиллионные" qualifies "инвестиции" (investments), indicating that these investments amount to a significant amount in the millions.
Город был основан на многомиллионные инвестиции.
The city was founded on multi-million investments.
In this sentence, "многомиллионные" describes "зрители" (viewers), referring to the fact that there were very many viewers, in terms of millions, watching the event.