The hex color #21725c is a dark color. The web-safe version is Hex
#336666. A complementary color is
#DE8DA3. The grayscale version is
#505050. A 20% lighter version of the original color is
#54A58F, and Hex
#003F29 is the 20% darker color. If the color is saturated by 10%, you get
#1C755D. If the color is desaturated by 10%, the color
#266F5B is obtained.