A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3403800 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 25 30 31 36 40 45 50 60 61 62 72 75 90 93 100 120 122 124 150 155 180 183 186 200 225 244 248 279 300 305 310 360 366 372 450 465 488 549 558 600 610 620 732 744 775 900 915 930 1,098 1,116 1,220 1,240 1,395 1,464 1,525 1,550 1,800 1,830 1,860 1,891 2,196 2,232 2,325 2,440 2,745 2,790 3,050 3,100 3,660 3,720 3,782 4,392 4,575 4,650 5,490 5,580 5,673 6,100 6,200 6,975 7,320 7,564 9,150 9,300 9,455 10,980 11,160 11,346 12,200 13,725 13,950 15,128 17,019 18,300 18,600 18,910 21,960 22,692 27,450 27,900 28,365 34,038 36,600 37,820 45,384 47,275 54,900 55,800 56,730 68,076 75,640 85,095 94,550 109,800 113,460 136,152 141,825 170,190 189,100 226,920 283,650 340,380 378,200 425,475 567,300 680,760 850,950 1,134,600 1,701,900 and 3,403,800, with no remainder.
Since 3,403,800 cannot be divided by just 1 and 3,403,800, it is not a prime number.