Hex #66bf4d or rgb(102,191,77) in RGB space is the tint of grass green. It has hue angle of 106.84 degrees, value = 75 and saturation = 60. #66bf4d can be obtained by mixing 4 colors: 1 drop of yellow, 5 drops of green, 3 drops of white, 1 drop of black.
Nearest safe hex - #66cc66. Below you can see the block with #66bf4d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66bf4d to the mixer and play with it.