A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7326540 can be evenly divided by 1 2 3 4 5 6 9 10 12 13 15 18 20 26 30 31 36 39 45 52 60 62 65 78 90 93 101 117 124 130 155 156 180 186 195 202 234 260 279 303 310 372 390 403 404 465 468 505 558 585 606 620 780 806 909 930 1,010 1,116 1,170 1,209 1,212 1,313 1,395 1,515 1,612 1,818 1,860 2,015 2,020 2,340 2,418 2,626 2,790 3,030 3,131 3,627 3,636 3,939 4,030 4,545 4,836 5,252 5,580 6,045 6,060 6,262 6,565 7,254 7,878 8,060 9,090 9,393 11,817 12,090 12,524 13,130 14,508 15,655 15,756 18,135 18,180 18,786 19,695 23,634 24,180 26,260 28,179 31,310 36,270 37,572 39,390 40,703 46,965 47,268 56,358 59,085 62,620 72,540 78,780 81,406 93,930 112,716 118,170 122,109 140,895 162,812 187,860 203,515 236,340 244,218 281,790 366,327 407,030 488,436 563,580 610,545 732,654 814,060 1,221,090 1,465,308 1,831,635 2,442,180 3,663,270 and 7,326,540, with no remainder.
Since 7,326,540 cannot be divided by just 1 and 7,326,540, it is not a prime number.