Search for a tool
Closest Prime Number

Tool to find the closest prime number of a number, the prime number nearest to a given number also called closest Prime function

Results

Closest Prime Number -

Tag(s) : Arithmetics

Share
Share
dCode and you

dCode is free and its tools are a valuable help in games, maths, geocaching, puzzles and problems to solve every day!
A suggestion ? a feedback ? a bug ? an idea ? Write to dCode!


Please, check our community Discord for help requests!


Thanks to your feedback and relevant comments, dCode has developped the best Closest Prime Number tool, so feel free to write! Thank you !

Closest Prime Number

Nearest Prime Number Finder


Tool to find the closest prime number of a number, the prime number nearest to a given number also called closest Prime function

Answers to Questions

How to calculate the closest prime number?

No mathematic formula can find the nearest prime number of another given number. dCode uses algorithms based on probabilistic primality tests for numbers higher or lower than the number requested, and then checks it via deterministic algorithms.

Example: The closest prime number to 100 is 101

Example: The nearest prime number to 1000 is 997 (the next is 1009)

Example: The closest prime number to 10000 is 10007

If the next prime number and the previous prime number are at the same distance, dCode returns the next prime number.

What are twin primes numbers?

Two prime numbers are called twins if their difference is 2 (the nearest prime number is at a distance of 2 units).

Example: 5 and 7 are twins because 7-5 = 2.

What is the sequence of closest prime numbers to N?

The OEIS lists 2 series of numbers:

A051697: 2, 2, 2, 3, 3, 5, 5, 7, 7, 7, 11, 11, 11, 13, ... which for any integer N associates its nearest prime number (the smallest in the case of a tie)

A077018: 2, 2, 2, 3, 5, 5, 7, 7, 7, 11, 11, 11, 13, 13, ... which for any integer N associates its nearest prime number (the largest in case of a tie)

The 2 sequences are identical except for the number 3 which appears twice in the first sequence but only once in the second one.

Source code

dCode retains ownership of the online 'Closest Prime Number' tool source code. Except explicit open source licence (indicated CC / Creative Commons / free), any algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any function (convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (PHP, Java, C#, Python, Javascript, Matlab, etc.) no data, script or API access will be for free, same for Closest Prime Number download for offline use on PC, tablet, iPhone or Android !

Need Help ?

Please, check our community Discord for help requests!

Questions / Comments

Thanks to your feedback and relevant comments, dCode has developped the best Closest Prime Number tool, so feel free to write! Thank you !


Source : https://www.dcode.fr/closest-prime-number
© 2020 dCode — The ultimate 'toolkit' to solve every games / riddles / geocaching / CTF.
Feedback