Selected Answer
I wrote a macro for this purpose in 2012. Below is a list of the words needed for the conversion (copied from that code)
Const Ones As String = "zero one two three four five six seven eight nine"
Const Teens As String = "teen eleven twelve thir four fif six seven eigh nine"
Const Tens As String = "null ten twenty thirty fourty fifty sixty seventy eighty ninety"
Const Powers As String = "hundred thousand million billion"
Const SpellCurr As String = "dollar,only,and,cent"
To save you the counting, there are 38 of them which must be arranged in logical order. Excel doesn't have a built-in function to do that and to construct one using Excel's worksheet functions seems like a daunting task, even if one presumes that you don't need billions and perhaps not even cents.
A reasonable solution would be the use of a UDF (User Defined Function) which is entered like an Excel worksheet function but works with VBA in the background. SpellNumber, which you mention, is such a UDF which you could download from the Internet.
My macro is more elaborate. It could be converted to be called like a UDF. The whole macro is available here, just in case your need is greater than your aversion to macros.