A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1172340 can be evenly divided by 1 2 3 4 5 6 9 10 12 13 15 18 20 26 27 30 36 39 45 52 54 60 65 78 90 108 117 130 135 156 167 180 195 234 260 270 334 351 390 468 501 540 585 668 702 780 835 1,002 1,170 1,404 1,503 1,670 1,755 2,004 2,171 2,340 2,505 3,006 3,340 3,510 4,342 4,509 5,010 6,012 6,513 7,020 7,515 8,684 9,018 10,020 10,855 13,026 15,030 18,036 19,539 21,710 22,545 26,052 30,060 32,565 39,078 43,420 45,090 58,617 65,130 78,156 90,180 97,695 117,234 130,260 195,390 234,468 293,085 390,780 586,170 and 1,172,340, with no remainder.
Since 1,172,340 cannot be divided by just 1 and 1,172,340, it is not a prime number.