Programatically check if object parameter is default(object.GetType()) in C#

Question

I'm writing an ObjectHasValueConverter : IValueConverter for WPF.

The relevant function is Convert(object value, ...). I want essentially want to do

return value != default(value.GetType())

Unfortunately, it seems default is a compile-time keyword and IValueConverter doesn't have a generic equivalent, so I can't just do default(T).

Obviously if value is an instance of a class or an array I can just check for null.

if (value.GetType().IsValueType | value.GetType().IsArray)
{
    return value != null;
}

I have a special case for strings, returning !string.IsNullOrWhitespace(value). For structs and other primitives, I'm hoping there's something cleaner than

if (value is int | value is short | value is long | ...)
{
    return (int)value != 0;
}

if (value is float | value is double)
{
    return (double)value != 0;
}

if (value is bool)
{
    return !(bool)value;
}
...

I've scoured SO before writing this, but all the answers I found had to do with reflection and getting the members of a value type. I didn't find anything relating to types that are put on the stack.