A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1481550 can be evenly divided by 1 2 3 5 6 7 10 14 15 17 21 25 30 34 35 42 50 51 70 75 83 85 102 105 119 150 166 170 175 210 238 249 255 350 357 415 425 498 510 525 581 595 714 830 850 1,050 1,162 1,190 1,245 1,275 1,411 1,743 1,785 2,075 2,490 2,550 2,822 2,905 2,975 3,486 3,570 4,150 4,233 5,810 5,950 6,225 7,055 8,466 8,715 8,925 9,877 12,450 14,110 14,525 17,430 17,850 19,754 21,165 29,050 29,631 35,275 42,330 43,575 49,385 59,262 70,550 87,150 98,770 105,825 148,155 211,650 246,925 296,310 493,850 740,775 and 1,481,550, with no remainder.
Since 1,481,550 cannot be divided by just 1 and 1,481,550, it is not a prime number.