Hex #556d8e or rgb(85,109,142) in RGB space is the tint of blue. It has hue angle of 214.74 degrees, value = 56 and saturation = 40. #556d8e can be obtained by mixing 3 colors: 1 drop of blue, 1 drop of white, 1 drop of black.
Nearest safe hex - #666699. Below you can see the block with #556d8e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556d8e to the mixer and play with it.