A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3546400 can be evenly divided by 1 2 4 5 8 10 11 13 16 20 22 25 26 31 32 40 44 50 52 55 62 65 80 88 100 104 110 124 130 143 155 160 176 200 208 220 248 260 275 286 310 325 341 352 400 403 416 440 496 520 550 572 620 650 682 715 775 800 806 880 992 1,040 1,100 1,144 1,240 1,300 1,364 1,430 1,550 1,612 1,705 1,760 2,015 2,080 2,200 2,288 2,480 2,600 2,728 2,860 3,100 3,224 3,410 3,575 4,030 4,400 4,433 4,576 4,960 5,200 5,456 5,720 6,200 6,448 6,820 7,150 8,060 8,525 8,800 8,866 10,075 10,400 10,912 11,440 12,400 12,896 13,640 14,300 16,120 17,050 17,732 20,150 22,165 22,880 24,800 27,280 28,600 32,240 34,100 35,464 40,300 44,330 54,560 57,200 64,480 68,200 70,928 80,600 88,660 110,825 114,400 136,400 141,856 161,200 177,320 221,650 272,800 322,400 354,640 443,300 709,280 886,600 1,773,200 and 3,546,400, with no remainder.
Since 3,546,400 cannot be divided by just 1 and 3,546,400, it is not a prime number.