If the heat from burning 6.000 g of

C6H6 2C6H6(l) + 15O2(g) -> 12CO2(g) + 6H2O(l) + 6542 kJ is added to 5691 g of water at 21 °C, what is the final temperature of the water?
Please tell me what I am doing wrong:
293,551= 5691*4.2*(Tf-21C)
293551= 23902.2Tf - 50946.2
343946.2= 23902.2Tf
14.4=Tf

The homework program is telling me it's wrong.