A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7646040 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 60 67 72 90 120 134 180 201 268 317 335 360 402 536 603 634 670 804 951 1,005 1,206 1,268 1,340 1,585 1,608 1,902 2,010 2,412 2,536 2,680 2,853 3,015 3,170 3,804 4,020 4,755 4,824 5,706 6,030 6,340 7,608 8,040 9,510 11,412 12,060 12,680 14,265 19,020 21,239 22,824 24,120 28,530 38,040 42,478 57,060 63,717 84,956 106,195 114,120 127,434 169,912 191,151 212,390 254,868 318,585 382,302 424,780 509,736 637,170 764,604 849,560 955,755 1,274,340 1,529,208 1,911,510 2,548,680 3,823,020 and 7,646,040, with no remainder.
Since 7,646,040 cannot be divided by just 1 and 7,646,040, it is not a prime number.