This is a jukugo word, which usually means on'yomi readings from the kanji. Since 人 has two on'yomi readings, here's a mnemonic to help you remember which one to use:
Imagine a white person you know well wearing their favorite pair of hacked up jeans (はくじん). This person likes to wear jeans with as many rips and holes in them as possible. Now imagine them wearing only their hacked up jeans. What a sight!
I married a white man.
I am black and from Kenya, but I was raised by a white family in America.
Many caucasians hate summer in Japan.