A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1046430 can be evenly divided by 1 2 3 5 6 7 9 10 11 14 15 18 21 22 30 33 35 42 45 55 63 66 70 77 90 99 105 110 126 151 154 165 198 210 231 302 315 330 385 453 462 495 630 693 755 770 906 990 1,057 1,155 1,359 1,386 1,510 1,661 2,114 2,265 2,310 2,718 3,171 3,322 3,465 4,530 4,983 5,285 6,342 6,795 6,930 8,305 9,513 9,966 10,570 11,627 13,590 14,949 15,855 16,610 19,026 23,254 24,915 29,898 31,710 34,881 47,565 49,830 58,135 69,762 74,745 95,130 104,643 116,270 149,490 174,405 209,286 348,810 523,215 and 1,046,430, with no remainder.
Since 1,046,430 cannot be divided by just 1 and 1,046,430, it is not a prime number.