Hex #55657b or rgb(85,101,123) in RGB space is the tint of blue. It has hue angle of 214.74 degrees, value = 48 and saturation = 31. #55657b can be obtained by mixing 3 colors: 2 drops of blue, 3 drops of white, 4 drops of black.
Nearest safe hex - #666666. Below you can see the block with #55657b color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #55657b to the mixer and play with it.