A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1742364 can be evenly divided by 1 2 3 4 6 9 12 13 17 18 26 27 34 36 39 51 52 54 68 73 78 102 108 117 146 153 156 204 219 221 234 292 306 351 438 442 459 468 612 657 663 702 876 884 918 949 1,241 1,314 1,326 1,404 1,836 1,898 1,971 1,989 2,482 2,628 2,652 2,847 3,723 3,796 3,942 3,978 4,964 5,694 5,967 7,446 7,884 7,956 8,541 11,169 11,388 11,934 14,892 16,133 17,082 22,338 23,868 25,623 32,266 33,507 34,164 44,676 48,399 51,246 64,532 67,014 96,798 102,492 134,028 145,197 193,596 290,394 435,591 580,788 871,182 and 1,742,364, with no remainder.
Since 1,742,364 cannot be divided by just 1 and 1,742,364, it is not a prime number.