Hex #66ac4d or rgb(102,172,77) in RGB space is the tint of grass green. It has hue angle of 104.21 degrees, value = 67 and saturation = 55. #66ac4d can be obtained by mixing 4 colors: 3 drops of yellow, 3 drops of blue, 3 drops of green, 1 drop of white.
Nearest safe hex - #669966. Below you can see the block with #66ac4d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66ac4d to the mixer and play with it.