It is a primorial.. It is a pronic number.. 30 is the smallest sphenic number, and the smallest of the form 2 × 3 × r, where r is a prime greater than 3. 30 has an aliquot sum of 42; the second sphenic number and all sphenic numbers of this form have an aliquot sum 12 greater than themselves.. Adding up some subsets of its divisors (e.g., 5, 10 and 15) gives 30, hence 30 is a semiperfect number.In the music industry, the top 40 is the current, 40 mostpopular songs in a particular genre. It is the bestselling or most frequently broadcast popular music. Record charts have traditionally consisted of a total of 40 songs. Top 40 or contemporary hit radio is also a radio format.Frequent variants of the Top 40 are the Top 10, Top 20, Top 30, Top 50, Top 75, Top 100 and Top 200.
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