Hex #66e9cc or rgb(102,233,204) in RGB space is the tint of greenish cian. It has hue angle of 166.72 degrees, value = 91 and saturation = 56. #66e9cc can be obtained by mixing 3 colors: 2 drops of cyan, 1 drop of green, 2 drops of white.
Nearest safe hex - #66ffcc. Below you can see the block with #66e9cc color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66e9cc to the mixer and play with it.