901

This number is a composite.

+ The only three-digit composite number (901 = 17*53) with a middle zero that gives only primes (9001, 90001, 900001), when up to three zeros are added in the middle.

+ Every number of the form (9+17n)01 (n an integer) has partial or complete prime factorization 17*n53. E.g., 4301 = 17*253 = 11*17*23, 6001 = 17*353, 9401 = 17*553 = 7*17*79, 101201 = 17*5953.

(There is one curio for this number that has not yet been approved by an editor.)

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