Judging from Pleco, outside of 参差, the character 参 is not pronounced cēn, and 差 is basically not pronounced cī. I did some basic Googling, and found webpages which say it's pronounced cēncī, but don't explain why it's pronounced cēncī. It seems to be in some ancient poetry (e.g. this), so maybe there's something special about it.
Question: Why is 参差 pronounced cēncī?