Mersenne Primes vs Thorium Reader
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Mersenne Primes
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.
- 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
Read full descriptionHide full description
Prime numbers are fundamentally important in mathematics and they are also very beautiful numbers. The largest known prime number we know now is 2^77232917-1 and it is a Mersenne Prime (a prime number of the form Mn = 2^n − 1 for some integer n which is also a prime number). The current largest Mersenne Prime number M77232917 (found in 2017 by GIMPS - Great Internet Mersenne Prime Search) has 23,249,425 digits. There is no website that can show you all the digits in a webpage because it is too huge. This app will generate and show you all digits of all known Mersenne Primes. You can also have close look of every digit page by page. The digits will be generated by your mobile phone's CPU and saved to your storage card. You will witness the whole process of the generation for the big ones (i.e. M77232917 , M74207281, M57885161, M43112609, M42643801, M37156667, ...), because it might need one day or two to print the digits all. You can also locate a digit by its sequence number. e.g. the 23249268th digit of M77232917 is 8.
Thorium Reader
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.
- 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
Read full descriptionHide full description
Looking for an app where you can bring all your ebooks, comics and manga in one place? That’s what we built Thorium Reader for. Read it your way Everyone’s different, that’s why we want you to be fully in control: • Adjust text size, switch between color schemes with themes and control spacing. • 10+ fonts available, including specialized ones. • You prefer audio? Listen to any ebook, whenever you want. We’ll remember your preference. • Zoom into comics, manga and magazines. • Add bookmarks with notes. • Use the built-in iOS dictionary and translation features, even offline. • Tweak your reading experience with reading options. Bring your own books A single bookshelf and reading application where you can bring all your content: • Download free books, borrow from your library or buy from your favorite retailer. • Support for ebooks, documents, comics and manga. • Import EPUB, PDF and CBZ files. • Support for Readium LCP, used by thousands of libraries and retailers. Thorium Reader is built by EDRLab, a non-profit dedicated to open standards, reading and accessibility.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Mersenne Primes | Thorium Reader |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | 3.5 (13 ratings) |
| Positive reviews | 100.0% of reviews — better | 40.0% of reviews |
| Number of ratings | 1 | 13 — better |
| Update frequency | Weekly — better | Every 3 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 9.0 — better | 26.1 |
| Further details — not scored | ||
| Size | 60 MB | 46 MB |
| Age rating | 4+ | 17+ |
| Developer | 华 魏 | Readium |
Customer experience
Mersenne Primes
Thorium Reader
In-app purchases
Mersenne Primes
- One Support$0.99
Thorium Reader
No in-app purchases
Questions
Is Mersenne Primes free?
Is Thorium Reader free?
Which has better reviews, Mersenne Primes or Thorium Reader?
Do Mersenne Primes or Thorium Reader have ads?
Which is updated more often, Mersenne Primes or Thorium Reader?
Other comparisons
