Создать в Excel функцию, получающую число и возвращающую ближайшее к полученному простое число

Sub Замена_пробелов()
 
Dim arrText() As Variant
arrText = Array("( ){2;}")
 
Dim arrReplaceText() As Variant
arrReplaceText = Array(" ")
 
Selection.WholeStory
 
For i = 0 To UBound(arrText)
 
 Selection.Find.ClearFormatting
 Selection.Find.Replacement.ClearFormatting
 With Selection.Find
 .Text = arrText(i)
 .Replacement.Text = arrReplaceText(i)
 .Forward = True
 .Wrap = wdFindContinue
 .Format = False
 .MatchCase = False
 .MatchWholeWord = False
 .MatchWildcards = True
 .MatchSoundsLike = False
 .MatchAllWordForms = False
 End With
 Selection.Find.Execute Replace:=wdReplaceAll
Next
 
End Sub

Function isPrime(n As Long) As Boolean
     If n > 2 And n Mod 2 = 0 Then
        isPrime = False
        Exit Function
     End If
     k& = 3
     Do While (k& * k& <= n)
        If n Mod k = 0 Then
           isPrime = False
           Exit Function
        End If
        k& = k& + 2
     Loop
     isPrime = True
End Function
 
Function nearestPrime(n As Long) As Long
     If isPrime(n) Then
        nearestPrime = n
        Exit Function
     End If
     k& = 1
     Do
        If isPrime(n + k&) Then
           nearestPrime = n + k&
           Exit Function
        End If
        If isPrime(n - k&) Then
           nearestPrime = n - k&
           Exit Function
        End If
        k& = k& + 1
     Loop
End Function
 
Sub Test()
 
    Debug.Print (nearestPrime(40))
    Debug.Print (nearestPrime(78))
 
End Sub

Function IsPrime(num As Long) As Boolean
    Dim i As Long
    If num <>2 then and num Mod 2 = 0 Then
        Exit Function
        Else
        For i = 3 To Sqr(num) Step 2
            If num Mod i = 0 Then
                Exit Function
            End If
        Next i
    End If
    IsPrime = True
End Function
 
Function NearestPrime(num As Long) As Long
    Dim UPrime As Long, LPrime As Long
    LPrime = num
    UPrime = num
    Do
        LPrime = LPrime - 1
        If LPrime > 1 Then
            If IsPrime(LPrime) Then
                NearestPrime = LPrime
                Exit Function
            End If
        End If
        UPrime = UPrime + 1
        If IsPrime(UPrime) Then
            NearestPrime = UPrime
            Exit Function
        End If
    Loop
End Function

Function IsPrime(num As Double) As Boolean
    Dim i As Long
    If num <> 2 And Int(num / 2) = num / 2 Then
        Exit Function
        Else
        For i = 3 To Sqr(num) Step 2
            If Int(num / i) = num / i Then
                Exit Function
            End If
        Next i
    End If
    IsPrime1 = True
End Function