XLII vs isPrime?
Price, ratings, monetisation and update history for both apps, side by side β with what reviewers say about each.
XLII
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XLII - Explore Numbers and Numerals help you learn about, discover, and explore number and numerals from around the world, ranging from familiar Roman numerals to the ancient KharoαΉ£αΉhΔ« script. You even can use your camera to scan numbers and convert them to an interesting output format.Β To achieve full immersion, use the XLII Clock widget to display the current date and time in a number format of your choosing directly in your Home Screen. XLII - Explore Numbers and Numerals supports: - Arabic numerals (naturally) - Roman numerals - Japanese numerals (including financial notation) - Babylonian Cuneiform numerals (base 60) - Aegean numerals (Linear B script) - Chinese counting rods (η±) - Egyptian Hieroglyphs - Suzhou numbers (θε·η’Όε) - Phoenician numbers - KharoαΉ£αΉhΔ« numerals - Brahmi numerals - Glagolitic numerals - Cyrillic numerals - Ge'ez numbers - Sundanese numbers - Tibetan numbers - Mongolian numbers - hexadecimal, binary, octal, vigesimal, etc. - spell-out notation for many languages Most formats are also accepted as input, e.g. you can convert from Roman to Cyrillic, from Ge'ez to binary, or from Japanese to Babylonian. Some (ancient) formats don't support large numbers.
isPrime?
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It's a fast prime number checker.
Screenshots
Verdict
The clearest difference is iOS requirement: isPrime? at 15.0 against XLII's 17.6. On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
XLII ships an update every 9 months, isPrime? every 16 months. The most recent releases landed on October 30, 2026 and October 25, 2026 respectively.
| Parameter | XLII | isPrime? |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 9 months β better | Every 16 months |
| Ads | No | No |
| In-app purchases | No | No |
| Devices | iPhone, iPad, Mac | iPhone, iPad, iPod |
| Requires iOS | 17.6 | 15.0 β better |
| Further details β not scored | ||
| Size | 15 MB | 4 MB |
| Age rating | 4+ | 4+ |
| Developer | telethon k.k. | Omer Faruk Mesebuken |
In-app purchases
XLII
No in-app purchases
isPrime?
No in-app purchases
