A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 383760 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 16 18 20 24 26 30 36 39 40 41 45 48 52 60 65 72 78 80 82 90 104 117 120 123 130 144 156 164 180 195 205 208 234 240 246 260 312 328 360 369 390 410 468 492 520 533 585 615 624 656 720 738 780 820 936 984 1,040 1,066 1,170 1,230 1,476 1,560 1,599 1,640 1,845 1,872 1,968 2,132 2,340 2,460 2,665 2,952 3,120 3,198 3,280 3,690 4,264 4,680 4,797 4,920 5,330 5,904 6,396 7,380 7,995 8,528 9,360 9,594 9,840 10,660 12,792 14,760 15,990 19,188 21,320 23,985 25,584 29,520 31,980 38,376 42,640 47,970 63,960 76,752 95,940 127,920 191,880 and 383,760, with no remainder.
Since 383,760 cannot be divided by just 1 and 383,760, it is not a prime number.