Today, having turned 27181 days old and also 3883 weeks old, I discovered that 27181 is a very special number indeed. It is a sphenic number with the property that when its three prime factors are concatenated in any order, the resultant numbers are all prime. The details are as follows:27181=7×11×353with the concatenated numbers thus being711353,735311,117353,113537,353711,353117
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My special sphenic numbers are 3311, 27181 and 32153 |
The other numbers up to one million are 41237, 53977, 86507, 110971, 125069, 208579, 256413, 500981, 543337, 853811, 901949 and 964481. The OEIS comments state that, for quadruply composite numbers, is no term with four distinct prime factors under one hundred million.
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