Hex #669591 or rgb(102,149,145) in RGB space is the tint of cyan. It has hue angle of 174.89 degrees, value = 58 and saturation = 32. #669591 can be obtained by mixing 4 colors: 1 drop of yellow, 3 drops of red, 1 drop of blue, 5 drops of cyan.
Nearest safe hex - #669999. Below you can see the block with #669591 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #669591 to the mixer and play with it.