42857

42857 is a five-digit decimal number. In the United States, five-digit sequences such as 42857 are commonly used as ZIP codes, assigned by the United States Postal Service to designate geographic delivery areas. ZIP codes facilitate mail routing, demographic analysis, and regional planning, and they can correspond to towns, rural regions, or portions of cities.

In mathematics, 42857 is a composite, odd integer. Its prime factorization is 17 × 2521, so it is divisible by 17 but not by 2, 3, 5, or 7. The sum of its digits is 26, giving a digital root of 8. The number is square-free, as its prime factors are distinct.

Beyond postal and mathematical contexts, 42857 may appear as a numeric identifier in data sets, product catalogs, or illustrative examples in educational materials. While it has specific numerical properties, there is no widely recognized historical, cultural, or scientific significance attached to the number 42857 as a standalone symbol.