A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2146680 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 60 67 72 89 90 120 134 178 180 201 267 268 335 356 360 402 445 534 536 603 670 712 801 804 890 1,005 1,068 1,206 1,335 1,340 1,602 1,608 1,780 2,010 2,136 2,412 2,670 2,680 3,015 3,204 3,560 4,005 4,020 4,824 5,340 5,963 6,030 6,408 8,010 8,040 10,680 11,926 12,060 16,020 17,889 23,852 24,120 29,815 32,040 35,778 47,704 53,667 59,630 71,556 89,445 107,334 119,260 143,112 178,890 214,668 238,520 268,335 357,780 429,336 536,670 715,560 1,073,340 and 2,146,680, with no remainder.
Since 2,146,680 cannot be divided by just 1 and 2,146,680, it is not a prime number.