A number 
is called equidigital if the number of digits in the prime factorization of 
(including powers) uses the same number
of digits as the number of digits in 
. The first few equidigital numbers are 1, 2, 3, 5, 7, 10,
11, 13, 14, 15, 16, 17, 19, 21, 23, ... (OEIS A046758).
Equidigital Number
See also
Economical Number, Wasteful NumberExplore with Wolfram|Alpha
References
Pinch, R. G. E. "Economical Numbers." http://www.chalcedon.demon.co.uk/publish.html#62.Santos, B. R. "Problem 2204. Equidigital Representation." J. Recr. Math. 27, 58-59, 1995.Sloane, N. J. A. Sequence A046758 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Equidigital NumberCite this as:
Weisstein, Eric W. "Equidigital Number." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/EquidigitalNumber.html