A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7812350 can be evenly divided by 1 2 5 7 10 13 14 17 25 26 34 35 50 65 70 85 91 101 119 130 170 175 182 202 221 238 325 350 425 442 455 505 595 650 707 850 910 1,010 1,105 1,190 1,313 1,414 1,547 1,717 2,210 2,275 2,525 2,626 2,975 3,094 3,434 3,535 4,550 5,050 5,525 5,950 6,565 7,070 7,735 8,585 9,191 11,050 12,019 13,130 15,470 17,170 17,675 18,382 22,321 24,038 32,825 35,350 38,675 42,925 44,642 45,955 60,095 65,650 77,350 85,850 91,910 111,605 120,190 156,247 223,210 229,775 300,475 312,494 459,550 558,025 600,950 781,235 1,116,050 1,562,470 3,906,175 and 7,812,350, with no remainder.
Since 7,812,350 cannot be divided by just 1 and 7,812,350, it is not a prime number.