Hex #66717d or rgb(102,113,125) in RGB space is the tint of blue. It has hue angle of 211.30 degrees, value = 49 and saturation = 18. #66717d can be obtained by mixing 4 colors: 4 drops of magenta, 4 drops of blue, 5 drops of green, 2 drops of white.
Nearest safe hex - #666666. Below you can see the block with #66717d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66717d to the mixer and play with it.