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An equidigital number is a number that has the same number of digits as the number of digits in its prime factorization (including exponents). For example, in base10 arithmetic 1, 2, 3, 5, 7, and 10 (2×5) are equidigital numbers. All prime numbers are equidigital numbers in any base. A number that is either equidigital or frugal is said to be economical. See also
References * R.G.E. Pinch (1998), Economical Numbers Retrieved from "http://en.wikipedia.org/"

