Comparison

Mersenne Primes vs Wordshelf

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

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
Read 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.

About

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.

Highlights
  • 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
Features
Read full description

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

Screenshots

Mersenne Primes4 screens
Wordshelf4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

Mersenne Primes ships an update weekly, Wordshelf every 4 days. The most recent releases landed on September 30, 2026 and October 16, 2026 respectively.

Scorecard5 real differences · 5 level
Mersenne Primes versus Wordshelf: the parameters behind the verdict, then further details
ParameterMersenne PrimesWordshelf
PriceFreeFree
Rating5.0 (1 ratings) — better4.9 (122 ratings)
Positive reviews100.0% of reviews100.0% of reviews
Number of ratings1122 — better
Update frequencyWeeklyEvery 4 days — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS9.0 — better17.0
Further details — not scored
Size60 MB110 MB
Age rating4+17+
Developer华 魏Sourse Labs LLC

Customer experience

Mersenne Primes

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews4 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Wordshelf

All ratings122 ratings
Positive98.4%
Neutral0.0%
Negative1.6%
Written reviews15 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

1 purchases

Mersenne Primes

One-time1
  • One Support$0.99
None

Wordshelf

No in-app purchases

Questions

Is Mersenne Primes free?
Mersenne Primes is free to download, with in-app purchases available.
Is Wordshelf free?
Wordshelf is free to download, with no in-app purchases.
Which has better reviews, Mersenne Primes or Wordshelf?
Mersenne Primes is rated higher. Mersenne Primes averages 5.0 out of 5 from 1 ratings, while Wordshelf averages 4.9 from 122 ratings.
Do Mersenne Primes or Wordshelf have ads?
Neither Mersenne Primes nor Wordshelf shows ads.
Which is updated more often, Mersenne Primes or Wordshelf?
Mersenne Primes ships an update weekly, and Wordshelf every 4 days. Most recently, Mersenne Primes was updated on September 30, 2026 and Wordshelf on October 16, 2026.

Other comparisons