The hex color #21746c is a dark color. The web-safe version is Hex
#336666. A complementary color is
#DE8B93. The grayscale version is
#565656. A 20% lighter version of the original color is
#54A79F, and Hex
#004139 is the 20% darker color. If the color is saturated by 10%, you get
#1C776E. If the color is desaturated by 10%, the color
#26716A is obtained.