# Mersenne Primes vs Thorium Reader

The clearest difference is review sentiment: Mersenne Primes at 100% against Thorium Reader's 40%. Mersenne Primes also leads on rating (5.0 vs 3.5) and update cadence (weekly vs every 3 weeks). Thorium Reader's advantage is in-app purchases (none vs 1) and ratings volume (13 vs 1). On price, ads and device support there is nothing between them.

Both are free to download. Mersenne Primes sells 1 one-off in-app purchase. Thorium Reader asks for nothing beyond the download.

Mersenne Primes holds the better App Store score, 5.0 against 3.5. That said, the two scores are not equally well evidenced: Thorium Reader has 13 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 100% of Mersenne Primes's written reviews are positive against 40% of Thorium Reader's.

Mersenne Primes ships an update weekly, Thorium Reader every 3 weeks. The most recent releases landed on November 11, 2026 and November 8, 2026 respectively.

## The numbers

| Metric | Mersenne Primes | Thorium Reader |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/mersenne-primes/id1362004527/reviews)** | [3.5 (13 ratings)](https://appshunter.io/ios/app/thorium-reader/id6745025189/reviews) |
| Number of ratings | 1 | **13** |
| Positive reviews | **100.0% of reviews** | 40.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Weekly** | Every 3 weeks |
| Monetization | Free with in-app purchases | **Free** |
| Size | 60 MB | 46 MB |
| Requires iOS | **9.0** | 26.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 17+ |
| Developer | [华 魏](https://appshunter.io/developer/454719266) | [Readium](https://appshunter.io/developer/1232183924) |

## What reviewers say

### Mersenne Primes

[App page](https://appshunter.io/ios/app/mersenne-primes/id1362004527)

Explore and view the digits of all known Mersenne prime numbers. Witness the generation process for extremely large primes, page by page, and locate specific digits by their sequence number.

**Highlights:** View all digits of known Mersenne Primes, Witness prime number generation process, Page-by-page digit exploration, Locate specific digits by sequence number, Generates primes using mobile CPU

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| One Support | $0.99 | one-time |


### Thorium Reader

[App page](https://appshunter.io/ios/app/thorium-reader/id6745025189)

Organize all your ebooks, comics, and manga in a single app. Customize your reading experience with adjustable text, fonts, and themes. Listen to audiobooks and zoom into visual content with ease.

**Highlights:** Unified bookshelf for all content, Adjustable text size and spacing, Multiple font options, Text-to-speech audio playback, Zoom for comics and manga, Offline dictionary and translation, Import EPUB, PDF, CBZ files

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Mersenne Primes free?

Mersenne Primes is free to download, with in-app purchases available.

### Is Thorium Reader free?

Thorium Reader is free to download, with no in-app purchases.

### Which has better reviews, Mersenne Primes or Thorium Reader?

Mersenne Primes is rated higher. Mersenne Primes averages 5.0 out of 5 from 1 ratings, while Thorium Reader averages 3.5 from 13 ratings.

### Do Mersenne Primes or Thorium Reader have ads?

Neither Mersenne Primes nor Thorium Reader shows ads.

### Which is updated more often, Mersenne Primes or Thorium Reader?

Mersenne Primes ships an update weekly, and Thorium Reader every 3 weeks. Most recently, Mersenne Primes was updated on November 11, 2026 and Thorium Reader on November 8, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*