Hex #556c80 or rgb(85,108,128) in RGB space is the tint of blue. It has hue angle of 207.91 degrees, value = 50 and saturation = 34. #556c80 can be obtained by mixing 4 colors: 1 drop of red, 3 drops of blue, 1 drop of green, 1 drop of white.
Nearest safe hex - #666699. Below you can see the block with #556c80 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556c80 to the mixer and play with it.