A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1906080 can be evenly divided by 1 2 3 4 5 6 8 10 11 12 15 16 19 20 22 24 30 32 33 38 40 44 48 55 57 60 66 76 80 88 95 96 110 114 120 132 152 160 165 176 190 209 220 228 240 264 285 304 330 352 361 380 418 440 456 480 528 570 608 627 660 722 760 836 880 912 1,045 1,056 1,083 1,140 1,254 1,320 1,444 1,520 1,672 1,760 1,805 1,824 2,090 2,166 2,280 2,508 2,640 2,888 3,040 3,135 3,344 3,610 3,971 4,180 4,332 4,560 5,016 5,280 5,415 5,776 6,270 6,688 7,220 7,942 8,360 8,664 9,120 10,032 10,830 11,552 11,913 12,540 14,440 15,884 16,720 17,328 19,855 20,064 21,660 23,826 25,080 28,880 31,768 33,440 34,656 39,710 43,320 47,652 50,160 57,760 59,565 63,536 79,420 86,640 95,304 100,320 119,130 127,072 158,840 173,280 190,608 238,260 317,680 381,216 476,520 635,360 953,040 and 1,906,080, with no remainder.
Since 1,906,080 cannot be divided by just 1 and 1,906,080, it is not a prime number.