30 is a square pyramidal number. 30 is an even, composite, pronic number.With 2, 3, and 5 as its prime factors, it is a regular number and the first sphenic number, the smallest of the form , where r is a prime greater than 3. It has an aliquot sum of 42; within an aliquot sequence of thirteen composite numbers (30, 42, 54, 66, 78, 90, 144, 259, 45, 33, 15, 9, 4, 3, 1, 0) to the Prime in the 3 ... More @Wikipedia
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