Hex #66bd33 or rgb(102,189,51) in RGB space is the tint of grass green. It has hue angle of 97.83 degrees, value = 74 and saturation = 73. #66bd33 can be obtained by mixing 4 colors: 2 drops of yellow, 5 drops of green, 2 drops of white, 1 drop of black.
Nearest safe hex - #66cc33. Below you can see the block with #66bd33 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66bd33 to the mixer and play with it.