A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2175348 can be evenly divided by 1 2 3 4 6 7 12 14 19 21 28 29 38 42 47 57 58 76 84 87 94 114 116 133 141 174 188 203 228 266 282 329 348 399 406 532 551 564 609 658 798 812 893 987 1,102 1,218 1,316 1,363 1,596 1,653 1,786 1,974 2,204 2,436 2,679 2,726 3,306 3,572 3,857 3,948 4,089 5,358 5,452 6,251 6,612 7,714 8,178 9,541 10,716 11,571 12,502 15,428 16,356 18,753 19,082 23,142 25,004 25,897 28,623 37,506 38,164 46,284 51,794 57,246 75,012 77,691 103,588 114,492 155,382 181,279 310,764 362,558 543,837 725,116 1,087,674 and 2,175,348, with no remainder.
Since 2,175,348 cannot be divided by just 1 and 2,175,348, it is not a prime number.