Hex #66d333 or rgb(102,211,51) in RGB space is the tint of grass green. It has hue angle of 100.88 degrees, value = 83 and saturation = 76. #66d333 can be obtained by mixing 4 colors: 3 drops of yellow, 1 drop of cyan, 5 drops of green, 1 drop of white.
Nearest safe hex - #66cc33. Below you can see the block with #66d333 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66d333 to the mixer and play with it.