CompositeQ

CompositeQ(n)

returns True if n is a composite integer number.

For very large numbers, CompositeQ uses probabilistic prime testing, so it might be wrong sometimes (i.e. a number might be non composite even though CompositeQ says it is).

See

• Wikipedia - Prime number

Examples

>> Select(Range(100), CompositeQ)
{4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,26,27,28,30,32,33,34,35,36,38,39,40,42,
44,45,46,48,49,50,51,52,54,55,56,57,58,60,62,63,64,65,66,68,69,70,72,74,75,76,77,
78,80,81,82,84,85,86,87,88,90,91,92,93,94,95,96,98,99,100}

CompositeQ has attribute Listable:

>> CompositeQ(Range(20))
{False,False,False,True,False,True,False,True,True,True,False,True,False,True,True,True,False,True,False,True}

Implementation status

• ✅ - full supported

Github

• Implementation of CompositeQ