Powerful number
Powerful number
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Powerful number

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Powerful number

144000 is a powerful number.
Every exponent in its prime factorization is larger than 1.
It is the product of a square and a cube.

A powerful number is a positive integer m such that for every prime number p dividing m, p2 also divides m. Equivalently, a powerful number is the product of a square and a cube, that is, a number m of the form m = a2b3, where a and b are positive integers. Powerful numbers are also known as squareful, square-full, or 2-full. Paul Erdős and George Szekeres studied such numbers and Solomon W. Golomb named such numbers powerful.

The following is a list of all powerful numbers between 1 and 1000:

If m = a2b3, then every prime in the prime factorization of a appears in the prime factorization of m with an exponent of at least two, and every prime in the prime factorization of b appears in the prime factorization of m with an exponent of at least three; therefore, m is powerful.

In the other direction, suppose that m is powerful, with prime factorization

where each αi ≥ 2. Define γi to be three if αi is odd, and zero otherwise, and define βi = αiγi. Then, all values βi are nonnegative even integers, and all values γi are either zero or three, so

supplies the desired representation of m as a product of a square and a cube.

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