Hex #66b955 or rgb(102,185,85) in RGB space is the tint of grass green. It has hue angle of 109.80 degrees, value = 73 and saturation = 54. #66b955 can be obtained by mixing 4 colors: 1 drop of yellow, 1 drop of blue, 2 drops of green, 1 drop of white.
Nearest safe hex - #66cc66. Below you can see the block with #66b955 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66b955 to the mixer and play with it.