not inconsiderable
Enough to be worthy of attention or consideration; quite large or significant. There is a not inconsiderable number of voters who feel they've been totally neglected over the past few years. The amount of time and money we've put into this venture is not inconsiderable.
not inconˈsiderable
(formal) large; large enough to be considered important: We have spent a not inconsiderable amount of money on the project already.