Hex #66be55 or rgb(102,190,85) in RGB space is the tint of grass green. It has hue angle of 110.29 degrees, value = 75 and saturation = 55. #66be55 can be obtained by mixing 4 colors: 4 drops of yellow, 2 drops of red, 5 drops of cyan, 4 drops of green.
Nearest safe hex - #66cc66. Below you can see the block with #66be55 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66be55 to the mixer and play with it.