Hex #404040 or rgb(64,64,64) in RGB space is the tint of red. It has hue angle of 0.00 degrees, value = 25 and saturation = 0. #404040 can be obtained by mixing 2 colors: 1 drop of white, 3 drops of black.
Nearest safe hex - #333333. Below you can see the block with #404040 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #404040 to the mixer and play with it.