A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7839552 can be evenly divided by 1 2 3 4 6 7 8 12 14 16 19 21 24 28 32 38 42 48 56 57 64 76 84 96 112 114 133 152 168 192 224 228 266 304 307 336 399 448 456 532 608 614 672 798 912 921 1,064 1,216 1,228 1,344 1,596 1,824 1,842 2,128 2,149 2,456 3,192 3,648 3,684 4,256 4,298 4,912 5,833 6,384 6,447 7,368 8,512 8,596 9,824 11,666 12,768 12,894 14,736 17,192 17,499 19,648 23,332 25,536 25,788 29,472 34,384 34,998 40,831 46,664 51,576 58,944 68,768 69,996 81,662 93,328 103,152 122,493 137,536 139,992 163,324 186,656 206,304 244,986 279,984 326,648 373,312 412,608 489,972 559,968 653,296 979,944 1,119,936 1,306,592 1,959,888 2,613,184 3,919,776 and 7,839,552, with no remainder.
Since 7,839,552 cannot be divided by just 1 and 7,839,552, it is not a prime number.