A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3745560 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 13 14 15 20 21 24 26 28 30 35 39 40 42 49 52 56 60 65 70 78 84 91 98 104 105 120 130 140 147 156 168 182 195 196 210 245 260 273 280 294 312 343 364 390 392 420 455 490 520 546 588 637 686 728 735 780 840 910 980 1,029 1,092 1,176 1,274 1,365 1,372 1,470 1,560 1,715 1,820 1,911 1,960 2,058 2,184 2,401 2,548 2,730 2,744 2,940 3,185 3,430 3,640 3,822 4,116 4,459 4,802 5,096 5,145 5,460 5,880 6,370 6,860 7,203 7,644 8,232 8,918 9,555 9,604 10,290 10,920 12,005 12,740 13,377 13,720 14,406 15,288 17,836 19,110 19,208 20,580 22,295 24,010 25,480 26,754 28,812 31,213 35,672 36,015 38,220 41,160 44,590 48,020 53,508 57,624 62,426 66,885 72,030 76,440 89,180 93,639 96,040 107,016 124,852 133,770 144,060 156,065 178,360 187,278 249,704 267,540 288,120 312,130 374,556 468,195 535,080 624,260 749,112 936,390 1,248,520 1,872,780 and 3,745,560, with no remainder.
Since 3,745,560 cannot be divided by just 1 and 3,745,560, it is not a prime number.