Hex #66a54d or rgb(102,165,77) in RGB space is the tint of grass green. It has hue angle of 102.95 degrees, value = 65 and saturation = 53. #66a54d can be obtained by mixing 4 colors: 2 drops of red, 1 drop of cyan, 5 drops of green, 2 drops of white.
Nearest safe hex - #669966. Below you can see the block with #66a54d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66a54d to the mixer and play with it.