R number output format

I'd like to save the number 0.0000012 to a file just as it appears:

?formatC
formatC(.000000012, format='fg')
[1] "0.000000012"

also

?sprintf
sprintf("%.10f", 0.0000000012)
[1] "0.0000000012"

or

format(.0000012, scientific=FALSE)
[1] "0.0000012"