The hex color #21c4fb is a light color. The web-safe version is Hex
#33CCFF. A complementary color is
#DE3B04. The grayscale version is
#A0A0A0. A 20% lighter version of the original color is
#54F7FF, and Hex
#0091C8 is the 20% darker color. If the color is saturated by 10%, you get
#14C8FF. If the color is desaturated by 10%, the color
#2EC0F2 is obtained.