Hex #66acd2 or rgb(102,172,210) in RGB space is the tint of bluish cian. It has hue angle of 201.11 degrees, value = 82 and saturation = 51. #66acd2 can be obtained by mixing 4 colors: 1 drop of red, 5 drops of blue, 4 drops of cyan, 5 drops of white.
Nearest safe hex - #6699cc. Below you can see the block with #66acd2 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66acd2 to the mixer and play with it.