NamedRange.NumberFormat property (excel interop)

Question

Hello,
I am having to hand craft an excel spreadsheet using COM interop - it is reasonably tedious but i have completed my work, with the exception of a single issue.  I have data that gets put in to a cell... this data is text.  My issue is with the NumberFormat property.  I cannot get it to display the data as text.  My input data is;
REF1456734TXT   -   (gets formatted in the cell fine)
28543500109      -  (gets formatted incorrectly)
I would like them to look exactly as above.  Annoyingly, if i use NumberFormat = "@", or NumberFormat = "General" It shows like this;

2.85435E+11

If i use NumberFormat = "#,##0"  it displays as  285,435,001.09.    I just want it to appear as textual... no formatting at all.  Can this be done?
Any help would be greatly appriciated!