A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1362636 can be evenly divided by 1 2 3 4 6 9 11 12 18 22 27 31 33 36 37 44 54 62 66 74 93 99 108 111 124 132 148 186 198 222 279 297 333 341 372 396 407 444 558 594 666 682 814 837 999 1,023 1,116 1,147 1,188 1,221 1,332 1,364 1,628 1,674 1,998 2,046 2,294 2,442 3,069 3,348 3,441 3,663 3,996 4,092 4,588 4,884 6,138 6,882 7,326 9,207 10,323 10,989 12,276 12,617 13,764 14,652 18,414 20,646 21,978 25,234 30,969 36,828 37,851 41,292 43,956 50,468 61,938 75,702 113,553 123,876 151,404 227,106 340,659 454,212 681,318 and 1,362,636, with no remainder.
Since 1,362,636 cannot be divided by just 1 and 1,362,636, it is not a prime number.