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Where 76831 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 76831 into a pocket calculator and turn it upside down: IEBgL — not quite a word, sorry.
- ➕ 76831 is a prime number. It cannot be divided by anything except 1 and itself. Its digits add up to 25, a total 2,242 other ZIP codes share.
- 💾In binary, the way a computer stores it:
10010110000011111 - 🏠 Its numerical neighbours: 76828 (Burkett, TX, 88 mi away) and 76832 (Cherokee, TX, 19 mi away).
- 🔄 Backwards, 76831 becomes 13867, which is not a ZIP code at all.
- 👥 43 other ZIP codes are made of exactly the same digits (13678, 13687, 13786, 16738, 16837, 16873, …). The farthest-flung twin is 13678 in Raymondville, NY, 1,621 miles away.
- 🧭 Farther south than 91% of all ZIP codes, and farther west than 79%.
- 🎯627 miles south of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 76831 and you would come out at 30.76°S, 81.04°E — 1,403 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
- ☀Longest day of the year: 14h 08m of daylight. Shortest: 10h 09m.
- 📏 At 8.2 square miles of land, 76831 is bigger than 25% of ZIP codes — room for about 6.2 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 0 |
|---|---|
| Households | 0 |
| Housing units | 0 |
| Population density | 0.0 / sq mi |
Business and tax activity
| Business establishments | 4This ZIP4 |
|---|---|
| Employees | 11This ZIP11 |
| Annual payroll | $496,000This ZIP$496,000 |
Land area
| Land area | 8.21 sq miThis ZIP8.21 sq mi |
|---|---|
| Water area | 0.02 sq miThis ZIP0.02 sq mi |
ZIP codes near 76831
| ZIP | City | Distance |
|---|---|---|
76820 | Art, TX | 5.3 mi |
76885 | Valley Spring, TX | 9.0 mi |
76869 | Pontotoc, TX | 10.6 mi |
76842 | Fredonia, TX | 14.3 mi |
78643 | Llano, TX | 15.4 mi |
76832 | Cherokee, TX | 18.9 mi |
76856 | Mason, TX | 19.3 mi |
76887 | Voca, TX | 22.4 mi |
78618 | Doss, TX | 22.6 mi |
78675 | Willow City, TX | 26.8 mi |
Find every ZIP code within 10 miles of 76831 →
Questions about this ZIP code
Where is ZIP code 76831?
76831 is in Castell, Texas, in Llano County. Its published point location is 30.7576, -98.9578.
What county is 76831 in?
76831 lies in Llano County.
What area code is 76831?
Castell uses area code 325, from NANPA's telephone records.
What time zone is 76831 in?
76831 uses America/Chicago.
How many people live in 76831?
About 0 people live in ZIP code 76831. These are American Community Survey 5-year estimates for the ZIP Code Tabulation Area, not a headcount.
What ZIP codes are near 76831?
The closest are 76820 (5.3 mi), 76885 (9 mi), 76869 (10.6 mi), 76842 (14.3 mi) and 78643 (15.4 mi).
Is 76831 a PO Box ZIP code?
76831 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “76831 ZIP Code — Castell, Texas (Llano County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/76831
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/76831.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.