Hex #66a64d or rgb(102,166,77) in RGB space is the tint of grass green. It has hue angle of 103.15 degrees, value = 65 and saturation = 54. #66a64d can be obtained by mixing 3 colors: 4 drops of yellow, 3 drops of cyan, 3 drops of black.
Nearest safe hex - #669966. Below you can see the block with #66a64d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66a64d to the mixer and play with it.