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Single Curio View: (Seek other curios for this number) 91 is the smallest nontrivial odd composite (that is, its prime factors [7, 13] are not, at first glance, obvious). Every smaller odd composite is either a familiar square, ends in 5, has a digit sum that is a multiple of 3, or is obviously divisible by 11.
Submitted: 20011026 19:34:13; Last Modified: 20080130 11:28:00.
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