A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6637650 can be evenly divided by 1 2 3 5 6 10 15 17 19 25 30 34 38 50 51 57 75 85 95 102 114 137 150 170 190 255 274 285 323 411 425 475 510 570 646 685 822 850 950 969 1,275 1,370 1,425 1,615 1,938 2,055 2,329 2,550 2,603 2,850 3,230 3,425 4,110 4,658 4,845 5,206 6,850 6,987 7,809 8,075 9,690 10,275 11,645 13,015 13,974 15,618 16,150 20,550 23,290 24,225 26,030 34,935 39,045 44,251 48,450 58,225 65,075 69,870 78,090 88,502 116,450 130,150 132,753 174,675 195,225 221,255 265,506 349,350 390,450 442,510 663,765 1,106,275 1,327,530 2,212,550 3,318,825 and 6,637,650, with no remainder.
Since 6,637,650 cannot be divided by just 1 and 6,637,650, it is not a prime number.