PrimeQ

PrimeQ[n] returns True if n is prime, False otherwise.

Attributes[PrimeQ] := {Listable, Protected}

Simple examples

In[1]:= PrimeQ[5]
Out[1]= True

In[2]:= PrimeQ[100]
Out[2]= False

In[3]:= PrimeQ[982451653]
Out[3]= True

In[4]:= PrimeQ[-2]
Out[4]= True

Further examples

PrimeQ only works for Integers:

In[1]:= PrimeQ[5.]
Out[1]= False