A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4286880 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 16 18 20 24 26 30 32 36 39 40 45 48 52 60 65 72 78 80 90 96 104 117 120 130 144 156 160 180 195 208 229 234 240 260 288 312 360 390 416 458 468 480 520 585 624 687 720 780 916 936 1,040 1,145 1,170 1,248 1,374 1,440 1,560 1,832 1,872 2,061 2,080 2,290 2,340 2,748 2,977 3,120 3,435 3,664 3,744 4,122 4,580 4,680 5,496 5,954 6,240 6,870 7,328 8,244 8,931 9,160 9,360 10,305 10,992 11,908 13,740 14,885 16,488 17,862 18,320 18,720 20,610 21,984 23,816 26,793 27,480 29,770 32,976 35,724 36,640 41,220 44,655 47,632 53,586 54,960 59,540 65,952 71,448 82,440 89,310 95,264 107,172 109,920 119,080 133,965 142,896 164,880 178,620 214,344 238,160 267,930 285,792 329,760 357,240 428,688 476,320 535,860 714,480 857,376 1,071,720 1,428,960 2,143,440 and 4,286,880, with no remainder.
Since 4,286,880 cannot be divided by just 1 and 4,286,880, it is not a prime number.