There is no simple formula for #919aa0, but we have one for color #9da5aa, that is similar to #919aa0 by 98.4%.
Color #9da5aa name: grayish blue
Hex #9da5aa or rgb(157,165,170) in RGB space is the tint of blue. It has hue angle of 203.08 degrees, value = 67 and saturation = 8. #9da5aa can be obtained by mixing 4 colors: 3 drops of yellow, 4 drops of magenta, 5 drops of cyan, 1 drop of white.
Nearest safe hex - #999999. Below you can see the block with #9da5aa color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #9da5aa to the mixer and play with it.