There is no simple formula for #989e98, but we have one for color #999f99, that is similar to #989e98 by 99.9%.
Color #999f99 name: grayish green
Hex #999f99 or rgb(153,159,153) in RGB space is the tint of green. It has hue angle of 120.00 degrees, value = 62 and saturation = 4. #999f99 can be obtained by mixing 4 colors: 5 drops of red, 5 drops of cyan, 1 drop of green, 4 drops of white.
Nearest safe hex - #999999. Below you can see the block with #999f99 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #999f99 to the mixer and play with it.