A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7527576 can be evenly divided by 1 2 3 4 6 7 8 12 14 21 24 28 37 42 49 56 74 84 98 111 147 148 168 173 196 222 259 294 296 346 392 444 518 519 588 692 777 888 1,036 1,038 1,176 1,211 1,384 1,554 1,813 2,072 2,076 2,422 3,108 3,626 3,633 4,152 4,844 5,439 6,216 6,401 7,252 7,266 8,477 9,688 10,878 12,802 14,504 14,532 16,954 19,203 21,756 25,431 25,604 29,064 33,908 38,406 43,512 44,807 50,862 51,208 67,816 76,812 89,614 101,724 134,421 153,624 179,228 203,448 268,842 313,649 358,456 537,684 627,298 940,947 1,075,368 1,254,596 1,881,894 2,509,192 3,763,788 and 7,527,576, with no remainder.
Since 7,527,576 cannot be divided by just 1 and 7,527,576, it is not a prime number.