A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2130128 can be evenly divided by 1 2 4 7 8 11 13 14 16 19 22 26 28 38 44 49 52 56 76 77 88 91 98 104 112 133 143 152 154 176 182 196 208 209 247 266 286 304 308 364 392 418 494 532 539 572 616 637 728 784 836 931 988 1,001 1,064 1,078 1,144 1,232 1,274 1,456 1,463 1,672 1,729 1,862 1,976 2,002 2,128 2,156 2,288 2,548 2,717 2,926 3,344 3,458 3,724 3,952 4,004 4,312 5,096 5,434 5,852 6,916 7,007 7,448 8,008 8,624 10,192 10,241 10,868 11,704 12,103 13,832 14,014 14,896 16,016 19,019 20,482 21,736 23,408 24,206 27,664 28,028 38,038 40,964 43,472 48,412 56,056 76,076 81,928 96,824 112,112 133,133 152,152 163,856 193,648 266,266 304,304 532,532 1,065,064 and 2,130,128, with no remainder.
Since 2,130,128 cannot be divided by just 1 and 2,130,128, it is not a prime number.