A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2087064 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 18 21 24 28 36 41 42 56 63 72 82 84 101 123 126 164 168 202 246 252 287 303 328 369 404 492 504 574 606 707 738 808 861 909 984 1,148 1,212 1,414 1,476 1,722 1,818 2,121 2,296 2,424 2,583 2,828 2,952 3,444 3,636 4,141 4,242 5,166 5,656 6,363 6,888 7,272 8,282 8,484 10,332 12,423 12,726 16,564 16,968 20,664 24,846 25,452 28,987 33,128 37,269 49,692 50,904 57,974 74,538 86,961 99,384 115,948 149,076 173,922 231,896 260,883 298,152 347,844 521,766 695,688 1,043,532 and 2,087,064, with no remainder.
Since 2,087,064 cannot be divided by just 1 and 2,087,064, it is not a prime number.