How does AutoHotKey determine if a copied string is a number?

How does AutoHotKey determine if a copied string is a number?

The following AutoHotKey snippet is supposed to:
Verify if copied string is a number
If so, search for that number in a website and in Windows Search.
Nothing happens. The If's expression is not seeing integers and bypasses
code.
Any ideas?
Send ^c
if ClipBoard is integer
{
Run, https://website/SREdit.jsp?id=%ClipBoard%
Run, search-ms:query=%ClipBoard%
}