A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7979400 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 13 15 18 20 22 24 25 26 30 31 33 36 39 40 44 45 50 52 55 60 62 65 66 72 75 78 88 90 93 99 100 104 110 117 120 124 130 132 143 150 155 156 165 180 186 195 198 200 220 225 234 248 260 264 275 279 286 300 310 312 325 330 341 360 372 390 396 403 429 440 450 465 468 495 520 550 558 572 585 600 620 650 660 682 715 744 775 780 792 806 825 858 900 930 936 975 990 1,023 1,100 1,116 1,144 1,170 1,209 1,240 1,287 1,300 1,320 1,364 1,395 1,430 1,550 1,560 1,612 1,650 1,705 1,716 1,800 1,860 1,950 1,980 2,015 2,046 2,145 2,200 2,232 2,325 2,340 2,418 2,475 2,574 2,600 2,728 2,790 2,860 2,925 3,069 3,100 3,224 3,300 3,410 3,432 3,575 3,627 3,720 3,900 3,960 4,030 4,092 4,290 4,433 4,650 4,680 4,836 4,950 5,115 5,148 5,580 5,720 5,850 6,045 6,138 6,200 6,435 6,600 6,820 6,975 7,150 7,254 7,800 8,060 8,184 8,525 8,580 8,866 9,300 9,672 9,900 10,075 10,230 10,296 10,725 11,160 11,700 12,090 12,276 12,870 13,299 13,640 13,950 14,300 14,508 15,345 16,120 17,050 17,160 17,732 18,135 18,600 19,800 20,150 20,460 21,450 22,165 23,400 24,180 24,552 25,575 25,740 26,598 27,900 28,600 29,016 30,225 30,690 32,175 34,100 35,464 36,270 39,897 40,300 40,920 42,900 44,330 48,360 51,150 51,480 53,196 55,800 60,450 61,380 64,350 66,495 68,200 72,540 76,725 79,794 80,600 85,800 88,660 90,675 102,300 106,392 110,825 120,900 122,760 128,700 132,990 145,080 153,450 159,588 177,320 181,350 199,485 204,600 221,650 241,800 257,400 265,980 306,900 319,176 332,475 362,700 398,970 443,300 531,960 613,800 664,950 725,400 797,940 886,600 997,425 1,329,900 1,595,880 1,994,850 2,659,800 3,989,700 and 7,979,400, with no remainder.
Since 7,979,400 cannot be divided by just 1 and 7,979,400, it is not a prime number.