A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7140408 can be evenly divided by 1 2 3 4 6 8 11 12 17 22 24 33 34 37 43 44 51 66 68 74 86 88 102 111 129 132 136 148 172 187 204 222 258 264 296 344 374 407 408 444 473 516 561 629 731 748 814 888 946 1,032 1,122 1,221 1,258 1,419 1,462 1,496 1,591 1,628 1,887 1,892 2,193 2,244 2,442 2,516 2,838 2,924 3,182 3,256 3,774 3,784 4,386 4,488 4,773 4,884 5,032 5,676 5,848 6,364 6,919 7,548 8,041 8,772 9,546 9,768 11,352 12,728 13,838 15,096 16,082 17,501 17,544 19,092 20,757 24,123 27,047 27,676 32,164 35,002 38,184 41,514 48,246 52,503 54,094 55,352 64,328 70,004 81,141 83,028 96,492 105,006 108,188 140,008 162,282 166,056 192,984 210,012 216,376 297,517 324,564 420,024 595,034 649,128 892,551 1,190,068 1,785,102 2,380,136 3,570,204 and 7,140,408, with no remainder.
Since 7,140,408 cannot be divided by just 1 and 7,140,408, it is not a prime number.