does it has any remix version?
Yes, she  recorded an official remix version for it.
We Belong Together
Carey recorded an official remix version for "We Belong Together", which she produced with DJ Clue. 
what album is we belong together by mariah carey on "The Emancipation of Mimi" who is the singer of this song? Mariah Carey
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We Belong Together [SEP] Remixes
Carey recorded an official remix version for "We Belong Together", which she produced with DJ Clue. The remix features vocals from rappers Jadakiss and Styles P, two-thirds of the hip-hop trio the LOX. The remix is fundamentally different from the original, described as having "a faster, springier backbeat" by Kelefa Sanneh of "The New York Times". Lyrically, the song is similar to the album version of the song, in which both rappers' verses contemplate on past memories. Styles P raps "Past is the past, just let it be bygones / Matter of fact I know a fly song that we could vibe on", which Sanneh writes "Cheerfully out of place, he sounds like a man who has wandered into the wrong summertime party, but so what? He figures he might as well stick around and enjoy it." In two separate reviews of "The Emancipation of Mimi", Sanneh referred to the song as both "great" and "excellent", in regards to the remix.