 # New Largest Prime Number Discovered - 23 million Digits

#### mosaix

##### Shropshire, U.K.
Supporter
At more than 23m digits long, the number is something of a beast. But for mathematicians, the latest discovery from a global gang of enthusiasts is a thing of beauty: the largest prime number ever found.

Known simply as M77232917, the figure is arrived at by calculating two to the power of 77,232,917 and subtracting one, leaving a gargantuan string of 23,249,425 digits.

Largest prime number discovered – with more than 23m digits

#### BAYLOR

##### There Are Always new Things to Learn.
At more than 23m digits long, the number is something of a beast. But for mathematicians, the latest discovery from a global gang of enthusiasts is a thing of beauty: the largest prime number ever found.

Known simply as M77232917, the figure is arrived at by calculating two to the power of 77,232,917 and subtracting one, leaving a gargantuan string of 23,249,425 digits.

Largest prime number discovered – with more than 23m digits

Math is not my strong point and please don't bit my head off for asking this. . But given that numbers go into infinity how can they say this is the largest ? Last edited:

#### Serendipity

Math is not my strong point and please don't bit my head off for asking this. . But given that numbers go into infinity how can they say this the largest ? It's the largest prime number that they've been able to calculate i.e. know all its digits. Yes, there are bigger prime numbers to be found, but we don't know what they look like.

[They used a standard formula that belongs to all prime numbers, which is why they were able to calculate it. I have a suspicion the group will go on to find the larger prime number, again using this formula as a basis.]

#### Venusian Broon

##### Defending the SF genre with terminal intensity
Supporter
Math is not my strong point and please don't bit my head off for asking this. . But given that numbers go into infinity how can they say this is the largest ? It's the largest right now. We don't know any bigger. So, until they find the next one.

But as there are infinite numbers of primes, we know that there are more that are larger. An infinite number more. Interestingly, however, we don't know if there are infinite numbers of Mersenne primes. (See below).

[They used a standard formula that belongs to all prime numbers, which is why they were able to calculate it. I have a suspicion the group will go on to find the larger prime number, again using this formula as a basis.]

That's definitely not true - that the formula belongs to all prime numbers - the prime in question is only the 50th Mersenne prime found. Thus the formula only applies to those fifty Mersenne Primes. There are definitely more than 50 known primes  . There are a great number of different 'prime templates'.

However, I do agree that it is likely that the next biggest Prime will come from further number-crunching on Mersenne Primes, as seems to be the go to for computational studies of massive prime numbers.

#### LordOfWizards

##### Well Known Rememberer
A prime number is a whole number greater than 1, whose only two whole-number factors are 1 and itself. So, by this definition would infinity be the largest prime number? (⚮/⚮ = 1) #### Venusian Broon

##### Defending the SF genre with terminal intensity
Supporter
A prime number is a whole number greater than 1, whose only two whole-number factors are 1 and itself. So, by this definition would infinity be the largest prime number? (⚮/⚮ = 1) Infinity is not a natural number (definitely in this case, as I am sure you are aware  - although there are a few spot in high mathematics that you can treat it as a number)

And infinity divided by infinity - very much like zero divided by zero - is not a number but undefined #### Biskit

##### Cat whisperer
Supporter
So, by this definition would infinity be the largest prime number? (⚮/⚮ = 1) Which infinity are we talking about. There's lots of them. • LordOfWizards

#### LordOfWizards

##### Well Known Rememberer
Yes of course I was being slightly cheeky. But I really like Biskit's answer. (Answer a question with a bigger question.)

If you ask Siri the question what is zero divided by zero in the iOS 8 operating system, the iPhone's virtual assistant will cleverly tell you that you're making no sense. “Imagine that you have zero cookies,” Siri's response begins, “and you split them evenly among zero friends...

#### tinkerdan

##### ∞<Q-Satis
“Imagine that you have zero cookies,” Siri's response begins, “and you split them evenly among zero friends...
::And they all have the same response, "Tastes like cotton candy."

I know this because I have zero friends.

• Parson

#### Venusian Broon

##### Defending the SF genre with terminal intensity
Supporter
If you ask Siri the question what is zero divided by zero in the iOS 8 operating system, the iPhone's virtual assistant will cleverly tell you that you're making no sense. “Imagine that you have zero cookies,” Siri's response begins, “and you split them evenly among zero friends...

0/0 being undefined isn't quite true, so don't take what Siri says as gospel , 'cause otherwise all of calculus would be undefined and useless (See Mathologer on Youtube, he did a lovely video on this stuff - and he included Siri's response in it too). But that's all about infinitesimals via limits and other processes rather than just thinking about the number zero by itself....but I'm going a bit technical, away from topic and probably confusing unless you've done calculus   #### LordOfWizards

##### Well Known Rememberer
VB - I've done Calculus. I've even tutored it. I know about limits (1/x as x approaches zero) and Integrals from a to b, where b equals infinity, etc. I haven't been heavily into the stuff for awhile, but I know what you mean. There are edge cases where more explanation or context is needed depending on what you are modeling. In fact, there's a joke I remember about limits: A teacher shows the student a formula (lim 8/x as x approaches 0 = ⚮) then asks what is (lim 5/x as x approaches 0). The student writes the 5 sideways since that seems to be what happened to the 8. It would be easier if I had a scratchpad to show you. (Do you get it?)

#### Parson

##### This world is not my home
Supporter
Sigh! Math humor? That must be the ultimate in oxymorons. (idly wonders if oxymorons is the name for math nerds.)

#### Venusian Broon

##### Defending the SF genre with terminal intensity
Supporter
(Do you get it?)

Yep #### LordOfWizards

##### Well Known Rememberer
Sigh! Math humor? That must be the ultimate in oxymorons. (idly wonders if oxymorons is the name for math nerds.)

Yes, Parson. I'm the ultimate OxyMoron. Careful, or I'll hit you with chemistry humor next. • Parson