Mersenne Primes vs Wordshelf
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
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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.
Wordshelf
Effortlessly capture, understand, and remember new words encountered while reading or studying. Utilize AI-powered mnemonics and visual aids to enhance retention. Track your vocabulary growth and organize learned words by the book you're reading.
- Scan pages or type words to look up
- Definitions, pronunciation, examples, synonyms, etymology
- Personalized AI mnemonics and memory images
- Words organized by book
- Vocabulary progress tracking
- Supports 20+ languages
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Learn smarter while you read. Wordshelf makes it effortless to capture, understand, and remember every new word you come across — whether you're reading a book, studying, or exploring ideas. HOW IT WORKS Scan any page with your camera to instantly identify and look up words, or type them in. Get definitions, pronunciation, examples, synonyms, and etymology. Each word gets a personalized mnemonic and AI-generated memory image to make it stick. Every word is saved and organized by the book you're reading. BUILT FOR READERS Unlike generic dictionary apps, Wordshelf is designed around how you actually read. Set your current book, and every word you look up is automatically linked to it. When you finish, you'll have a beautiful collection of everything you learned. REMEMBER MORE WITH AI Each word gets a custom mnemonic using the keyword method — linking the word's sound to a vivid mental image. Plus an AI-generated illustration to reinforce it. No more forgetting words you've looked up before. TRACK YOUR PROGRESS Watch your vocabulary grow with a visual activity grid. See your streaks, total words learned, word difficulty stats, and books completed at a glance. 20+ LANGUAGES Supports English, Spanish, French, German, Japanese, Korean, Chinese, Arabic, Hindi, Portuguese, and more. Start building your vocabulary today. Every book you read becomes an opportunity to learn. Terms of Use: https://wordshelfapp.com/terms Privacy Policy: https://wordshelfapp.com/privacy
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Verdict
The clearest difference is in-app purchases: Wordshelf at none against Mersenne Primes's 1. Wordshelf also leads on ratings volume (122 vs 1) and update cadence (every 4 days vs weekly). Mersenne Primes's advantage is iOS requirement (9.0 vs 17.0). On price, rating, review sentiment and ads 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. Wordshelf asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for Mersenne Primes against 4.9 for Wordshelf. That said, the two scores are not equally well evidenced: Wordshelf has 122 ratings behind it against 1, so its average is the more settled of the two. Written reviews split almost evenly too, at 100% and 100% positive.
Mersenne Primes ships an update weekly, Wordshelf every 4 days. The most recent releases landed on September 30, 2026 and October 16, 2026 respectively.
| Parameter | Mersenne Primes | Wordshelf |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | 4.9 (122 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 1 | 122 — better |
| Update frequency | Weekly | Every 4 days — better |
| 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 | 17.0 |
| Further details — not scored | ||
| Size | 60 MB | 110 MB |
| Age rating | 4+ | 17+ |
| Developer | 华 魏 | Sourse Labs LLC |
Customer experience
Mersenne Primes
Wordshelf
In-app purchases
Mersenne Primes
- One Support$0.99
Wordshelf
No in-app purchases
Questions
Is Mersenne Primes free?
Is Wordshelf free?
Which has better reviews, Mersenne Primes or Wordshelf?
Do Mersenne Primes or Wordshelf have ads?
Which is updated more often, Mersenne Primes or Wordshelf?
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