Hex #66dc91 or rgb(102,220,145) in RGB space is the tint of bluish green. It has hue angle of 141.86 degrees, value = 86 and saturation = 54. #66dc91 can be obtained by mixing 3 colors: 4 drops of yellow, 1 drop of blue, 5 drops of cyan.
Nearest safe hex - #66cc99. Below you can see the block with #66dc91 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66dc91 to the mixer and play with it.