Here You can set color in RGB color model and watch at complimentary colors at bottom of the page or just click random color.
Basic color:
#336881; rgb(51,104,129); hsl(199,43%,35%);
black
black
white
white
Complementary colors:
Analogous harmony (H+30):
#334080; rgb(51,64,128); hsl(229,43%,35%);
black
black
white
white
Analogous harmony (H-30):
#338072; rgb(51,128,114); hsl(169,43%,35%);
black
black
white
white
Triadic harmony (H+120):
#803366; rgb(128,51,102); hsl(319,43%,35%);
black
black
white
white
Triadic harmony (H-120):
#678033; rgb(103,128,51); hsl(79,43%,35%);
black
black
white
white
Split complements harmony (H+150):
#803340; rgb(128,51,64); hsl(349,43%,35%);
black
black
white
white
Split complements harmony (H-150):
#807233; rgb(128,114,51); hsl(49,43%,35%);
black
black
white
white
Complement harmony (H+180):
#804b33; rgb(128,75,51); hsl(19,43%,35%);
black
black
white
white
Monochromatic harmony (S+30):
#18709a; rgb(24,112,154); hsl(199,73%,35%);
black
black
white
white
Monochromatic harmony (S-30):
#4e5d65; rgb(78,93,101); hsl(199,13%,35%);
black
black
white
white
Monochromatic harmony (L+10):
#4184a4; rgb(65,132,164); hsl(199,43%,45%);
black
black
white
white
Monochromatic harmony (L-10):
#24495b; rgb(36,73,91); hsl(199,43%,25%);
black
black
white
white