Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: primep (<n>) Primality test. If primep (<n>) returns false, <n> is a composite number and if it returns true, <n> is a prime number with very high probability.

For <n> less than 341550071728321 a deterministic version of Miller-Rabins test is used. If primep (<n>) returns true, then <n> is a prime number.
For <n> bigger than 341550071728321 primep uses primep_number_of_tests Miller-Rabins pseudo-primality tests and one Lucas pseudo-primality test. The probability that <n> will pass one Miller-Rabin test is less than 1/4. Using the default value 25 for primep_number_of_tests, the probability of <n> beeing composite is much smaller that 10^-15.
There are also some inexact matches for primep. Try ?? primep to see them.
(%o1) true (%i2)