The hex color #3721b0 is a dark color. The web-safe version is Hex
#333399. A complementary color is
#C8DE4F. The grayscale version is
#585858. A 20% lighter version of the original color is
#6A54E3, and Hex
#04007D is the 20% darker color. If the color is saturated by 10%, you get
#341CB9. If the color is desaturated by 10%, the color
#3A27A7 is obtained.