A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2530836 can be evenly divided by 1 2 3 4 6 7 9 11 12 14 18 21 22 28 33 36 42 44 63 66 77 83 84 99 121 126 132 154 166 198 231 242 249 252 308 332 363 396 462 484 498 581 693 726 747 847 913 924 996 1,089 1,162 1,386 1,452 1,494 1,694 1,743 1,826 2,178 2,324 2,541 2,739 2,772 2,988 3,388 3,486 3,652 4,356 5,082 5,229 5,478 6,391 6,972 7,623 8,217 10,043 10,164 10,458 10,956 12,782 15,246 16,434 19,173 20,086 20,916 25,564 30,129 30,492 32,868 38,346 40,172 57,519 60,258 70,301 76,692 90,387 115,038 120,516 140,602 180,774 210,903 230,076 281,204 361,548 421,806 632,709 843,612 1,265,418 and 2,530,836, with no remainder.
Since 2,530,836 cannot be divided by just 1 and 2,530,836, it is not a prime number.