Outputting factors and prime factors of number into one cell

Hi, I've been trying to produce the factors of a number into a single cell. I have found the one for outputting them into a column, but need a few thousand, so cant have it in this format. I need randbetween(1,100) in column A and the factors in B. So A1=12 B1=1,2,3,4,6,12. The commas don't necessarily need to be there.

I also will need in the next step produce Prime factors in one single cell. Eg A1=12 B1=2, 2, 6

Sorry if it's been asked before, but I've had a search and can't quite find what I need.

Thanks in advance!

Sorry. I need all the factors.

But thinking about it, I will need Prime factors also in the same format in the not too distant future so if you know a way to do either that would be great!

Thanks

Put this in a code module:

Function Factors(ByVal dNum As Double, Optional bRevOrder As Boolean = False) As Variant
    ' shg 2006-0923
    '     2006-0604 - added bRevOrder argument
    ' Returns a comma-delimited string of the factors of dNum

    Dim vFac    As Variant

    vFac = IsPrime(dNum, True)

    Select Case VarType(vFac)
        Case vbError, vbString
            Factors = vFac

        Case Else
            Do Until VarType(vFac) = vbBoolean
                If bRevOrder Then
                    Factors = "," & CStr(vFac) & Factors
                Else
                    Factors = Factors & CStr(vFac) & ","
                End If
                dNum = dNum / vFac
                vFac = IsPrime(dNum, True)
            Loop

            If bRevOrder Then
                Factors = CStr(dNum) & Factors
            Else
                Factors = Factors & CStr(dNum)
            End If

    End Select
End Function

Function IsPrime(dNum As Double, Optional bFirstFactor As Boolean = False) As Variant
    ' shg 2006-0923
    '     2009-0603 fixed bug so if dNum Mod 15 = 0, returns 3 as a factor, not 5

    ' Returns:      if dNum is:
    '   #VALUE!       < 2
    '   "Too big!"    > 1E+15
    '   #VALUE!       <> Int(dNum)
    '   FALSE         composite and bFirstFactor is False or omitted
    '   1st factor    composite and bFirstFactor is True
    '   TRUE          prime and <= 1E+15

    Dim dQuo    As Double
    Dim dFac    As Double

    If dNum < 2# Or Int(dNum) <> dNum Then
        IsPrime = CVErr(xlErrValue)

    ElseIf dNum = 2# Or dNum = 5# Then
        IsPrime = True

    ElseIf dNum > 1E+15 Then
        IsPrime = "Too big!"

    Else
        ' can't use Mod with numbers bigger than Longs, so ...
        Select Case Right(CStr(dNum), 1)
            Case "0", "2", "4", "6", "8"
                IsPrime = IIf(bFirstFactor, 2#, False)

            Case "5"
                If bFirstFactor Then
                    dQuo = dNum / 3#
                    IsPrime = IIf(Int(dQuo) = dQuo, 3#, 5#)
                Else
                    IsPrime = False
                End If

            Case Else
                For dFac = 3# To Int(Sqr(dNum)) Step 2#
                    dQuo = dNum / dFac
                    If Int(dQuo) = dQuo Then
                        IsPrime = IIf(bFirstFactor, dFac, False)
                        Exit Function    '------------------------------------->
                    End If
                Next dFac

                IsPrime = True
        End Select
    End If
End Function

If A1 contains 123331060025819, then =Factors(A1) returns 113,12517,87195439

Ok, Sorry but I'm a bit of a novice when it comes to this, but I have opened my macros screen thing, copied n pasted the code. Now what do I do? I used a bit of initiative and found the =isprime so typed that into the cell, but it just come out as 'true' or 'false' not with the actual factors.

Thanks very much!

Alt F11 is the shortcut. Then insert a module and paste it in.

Nice code, shg!