The hex color #51a665 is a light color. The web-safe version is Hex
#669966. A complementary color is
#AE599A. The grayscale version is
#747474. A 20% lighter version of the original color is
#84D998, and Hex
#1E7332 is the 20% darker color. If the color is saturated by 10%, you get
#4EAB64. If the color is desaturated by 10%, the color
#55A167 is obtained.