Hex #66d733 or rgb(102,215,51) in RGB space is the tint of grass green. It has hue angle of 101.34 degrees, value = 84 and saturation = 76. #66d733 can be obtained by mixing 3 colors: 2 drops of yellow, 1 drop of cyan, 2 drops of green.
Nearest safe hex - #66cc33. Below you can see the block with #66d733 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66d733 to the mixer and play with it.