A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3557760 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 17 20 24 30 32 34 40 48 51 60 64 68 80 85 96 102 109 120 128 136 160 170 192 204 218 240 255 272 320 327 340 384 408 436 480 510 544 545 640 654 680 816 872 960 1,020 1,088 1,090 1,308 1,360 1,632 1,635 1,744 1,853 1,920 2,040 2,176 2,180 2,616 2,720 3,264 3,270 3,488 3,706 4,080 4,360 5,232 5,440 5,559 6,528 6,540 6,976 7,412 8,160 8,720 9,265 10,464 10,880 11,118 13,080 13,952 14,824 16,320 17,440 18,530 20,928 22,236 26,160 27,795 29,648 32,640 34,880 37,060 41,856 44,472 52,320 55,590 59,296 69,760 74,120 88,944 104,640 111,180 118,592 148,240 177,888 209,280 222,360 237,184 296,480 355,776 444,720 592,960 711,552 889,440 1,185,920 1,778,880 and 3,557,760, with no remainder.
Since 3,557,760 cannot be divided by just 1 and 3,557,760, it is not a prime number.