The prayer of a person in congregation is twenty-seven times in excess to the prayer said alone. (Using translation from Muslim 650b)
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «صَلَاةُ الرَّجُلِ فِي جَمَاعَةٍ تَزِيدُ عَلَى صَلَاتِهِ وَحْدَهُ سَبْعًا وَعِشْرِينَ دَرَجَةً»