The hex color #21557c is a dark color. The web-safe version is Hex
#336666. A complementary color is
#DEAA83. The grayscale version is
#515151. A 20% lighter version of the original color is
#5488AF, and Hex
#002249 is the 20% darker color. If the color is saturated by 10%, you get
#1C5580. If the color is desaturated by 10%, the color
#265578 is obtained.