Hex #5b91b0 or rgb(91,145,176) in RGB space is the tint of bluish cian. It has hue angle of 201.88 degrees, value = 69 and saturation = 48. #5b91b0 can be obtained by mixing 4 colors: 4 drops of blue, 2 drops of cyan, 5 drops of white, 3 drops of black.
Nearest safe hex - #669999. Below you can see the block with #5b91b0 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #5b91b0 to the mixer and play with it.