Frugal number
From Wikipedia, the free encyclopedia
Divisibility-based sets of integers |
Form of factorization: |
Prime number |
Composite number |
Powerful number |
Square-free number |
Achilles number |
Constrained divisor sums: |
Perfect number |
Almost perfect number |
Quasiperfect number |
Multiply perfect number |
Hyperperfect number |
Superperfect number |
Unitary perfect number |
Semiperfect number |
Primitive semiperfect number |
Practical number |
Numbers with many divisors: |
Abundant number |
Highly abundant number |
Superabundant number |
Colossally abundant number |
Highly composite number |
Superior highly composite number |
Other: |
Deficient number |
Weird number |
Amicable number |
Friendly number |
Sociable number |
Solitary number |
Sublime number |
Harmonic divisor number |
Frugal number |
Equidigital number |
Extravagant number |
See also: |
Divisor function |
Divisor |
Prime factor |
Factorization |
A frugal number is a natural number that has more digits than the number of digits in its prime factorization (including exponents). For example, using base-10 arithmetic, the first few frugal numbers are 125 (53), 128 (27), 243 (35), and 256 (28). Frugal numbers also exist in other bases; for instance, in binary arithmetic thirty-two is a frugal number, since 10101 = 100000.
The base-10 frugal numbers up to 2000 are:
- 125, 128, 243, 256, 343, 512, 625, 729, 1024, 1029, 1215, 1250, 1280, 1331, 1369, 1458, 1536, 1681, 1701, 1715, 1792, 1849, 1875 (sequence A046759 in OEIS)
The term economical number has been used about a frugal number, but also about a number which is either frugal or equidigital.
[edit] See also
[edit] References
- R.G.E. Pinch (1998), Economical Numbers