Is x prime?

Please try our number cruncher. If your question is more complex then try using the contact form. I can't promise a quick response though.

Can I have a copy of all 1.4 billion prime numbers that are on this site?

Yes, but due to it's size it is only available as a bit torrent. The file is in the format of 1 prime number per line and can be downloaded here: Torrent. We have also compressed it using 7zip, if you don't have this fantastic open source software then it can be downloaded from

I've taken the time to send you an email. Why haven't you responded?!

I apologise, I run this site in what little spare time I have. I read every email and do intend to respond to all emails. I have a backlog of about 6 months at the moment.

I've found a bug/mistake on!

Please send me an email using the contact form.

What is the first set of 100 numbers (e.g. 100-199, 1300-1399, 312300-312399) that does not contain a prime number?

The first occurrence is between the prime numbers 1671781 and 1671907 on this page (near bottom of 3rd column).

What is the smallest prime number that contains all digits 0 to 9 in sequence?


What percentage of prime numbers end in 1,3,7 and 9?

25% of prime numbers end in a 1
25% of prime numbers end in a 3
25% of prime numbers end in a 7
25% of prime numbers end in a 9