I don't know a function that does it, but you can change the number to binary,
and separate into 3 bytes the first one (leftmost) is the BLUE value, the middle one is the GREEN value and the last one is the RED value, of course changed back to decimal

for example

If you have 65793 as the color value, you change it to binary

Blue Green Red
00000001 00000001 00000001

so this is RGB(1,1,1)