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Where 21660 is
Approximate ZIP boundary (Census ZCTA 2020). ZIP codes are mail routes, not areas, so the shape shown is the Census tabulation area that approximates it.
- 🔢 Type 21660 into a pocket calculator and turn it upside down: OggIZ — not quite a word, sorry.
- ➕ As a number, 21,660 = 2 × 2 × 3 × 5 × 19 × 19. Its digits add up to 15, a total 1,657 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101010010011100 - 🏠 Its numerical neighbours: 21659 (Rhodesdale, MD, 27 mi away) and 21661 (Rock Hall, MD, 20 mi away).
- 🔄 Backwards, 21660 becomes 06612 — and that is a real ZIP code: Easton, CT, 210 miles away.
- 👥 31 other ZIP codes are made of exactly the same digits (01266, 02661, 06126, 06612, 12066, 16260, …). The farthest-flung twin is 66021 in Edgerton, KS, 1,027 miles away.
- 🧭 Farther south than 51% of all ZIP codes, and farther east than 85%.
- 🎯1,210 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21660 and you would come out at 38.96°S, 104.11°E — 818 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 54m of daylight. Shortest: 9h 26m.
- 📏 At 32.7 square miles of land, 21660 is bigger than 48% of ZIP codes — room for about 25 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 4,132This ZIP4,132 |
|---|---|
| Households | 1,457This ZIP1,457 |
| Housing units | 1,516This ZIP1,516 |
| Median age | 35.6This ZIP35.6Maryland39.4US 38.9 |
| Median household income | $80,469This ZIP$80,469Maryland$103,678US $80,734 |
| Median home value | $359,300This ZIP$359,300Maryland$419,900US $332,700 |
| Median gross rent | $945This ZIP$945Maryland$1,705US $1,413 |
| Bachelor's degree or higher | 17.3%This ZIP17.3% |
| Mean commute | 39.9 minThis ZIP39.9 min |
| Population density | 126.5 / sq miThis ZIP126.5 / sq mi |
Business and tax activity
| Business establishments | 69This ZIP69 |
|---|---|
| Employees | 861This ZIP861 |
| Annual payroll | $43,083,000This ZIP$43,083,000 |
| Tax returns filed | 1,980This ZIP1,980 |
| Total adjusted gross income | $136,138,000This ZIP$136,138,000 |
Land area
| Land area | 32.66 sq miThis ZIP32.66 sq mi |
|---|---|
| Water area | 0.04 sq miThis ZIP0.04 sq mi |
Other place names in 21660
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 21660
| ZIP | City | Distance |
|---|---|---|
21641 | Hillsboro, MD | 3.9 mi |
21657 | Queen Anne, MD | 5.1 mi |
21639 | Greensboro, MD | 5.7 mi |
21636 | Goldsboro, MD | 6.4 mi |
21629 | Denton, MD | 7.6 mi |
21625 | Cordova, MD | 8.1 mi |
21640 | Henderson, MD | 8.6 mi |
21617 | Centreville, MD | 10.5 mi |
21644 | Ingleside, MD | 11.2 mi |
21679 | Wye Mills, MD | 11.3 mi |
Find every ZIP code within 10 miles of 21660 →
Questions about this ZIP code
Where is ZIP code 21660?
21660 is in Ridgely, Maryland, in Caroline County. Its published point location is 38.9562, -75.8889.
What county is 21660 in?
21660 lies in Caroline County.
What area code is 21660?
Ridgely uses area codes 667 and 410, from NANPA's telephone records.
What time zone is 21660 in?
21660 uses America/New_York.
How many people live in 21660?
About 4,132 people live in ZIP code 21660, in 1,457 households, at 126.5 people per square mile. These are American Community Survey 5-year estimates for the ZIP Code Tabulation Area, not a headcount.
What is the median household income in 21660?
$80,469 a year, against $103,678 across Maryland.
What ZIP codes are near 21660?
The closest are 21641 (3.9 mi), 21657 (5.1 mi), 21639 (5.7 mi), 21636 (6.4 mi) and 21629 (7.6 mi).
Is 21660 a PO Box ZIP code?
21660 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21660 ZIP Code — Ridgely, Maryland (Caroline County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21660
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21660.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.