10000...00027 (84-digits)

This number is a prime.

                                                             1000 0000000000
0000000000 0000000000 0000000000 0000000000 0000000000 0000000000 0000000027

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If we concatenate the month and (two digit) day of the 27th October, we get 1027, a composite number. If zeros are inserted between the day and the year, 80 are required before a prime number is reached. This is more than for any other day of the year, with the possible exception of 1 October. [Hartley]