is_prime_number(9)

💖 is_prime_number 💖

okay so bestie, this is the is_prime_number(9) page from the Kernel API Manual, and it's literally here to tell you whether a number is prime. no cap 🧚✨

✨ NAME ✨

is_prime_number — test whether the given number is prime 💅

🌸 SYNOPSIS 🌸

bool is_prime_number (unsigned long x );

🎀 ARGUMENTS 🎀

• x — the number to test. that's the one, bestie 🔍

🦋 DESCRIPTION 🦋

so a prime number is an integer greater than 1 that is only divisible by itself and 1. periodt 💯

internally, a cache of prime numbers is kept — and yes, it's there to speed up searching for sequential primes, see next_prime_number — but if the number falls outside of that cache, its primality is tested using trial-divison. iconic behavior, honestly. 🧮✨

🌈 RETURN 🌈

• true if x is prime 🔥
• false for composite numbers 💀

👑 SEE ALSO 👑

• Kernel file ./lib/math/prime_numbers.c
• next_prime_number(9)

this cutie lives under ./lib/math, was dated October 2026, and the page is is_prime_number(9) 🫶💜