Showing exact filesize in bytes instead of shortform in directory listing

[Cie <cie@xxxxxxxxxxxxx>]

In Apache server 2.4, when activating the IndexOptions +FancyIndexing in the httpd.conf, the directory listing shows the file size of a file like in the following example:

exported_file.pdf 2.1M

The file size display is accumulated to Kilobytes (K) or Megabyte (M). The exact file size is 2176555 bytes, but instead "2.1M" is shown.

Is there a way to configure Apache server to show the exact file size in bytes in the directory listing?
I had a look into the Apache documentation of [mod_autoindex] http://httpd.apache.org/docs/2.4/mod/mod_autoindex.html but have not found anything suitable.

Background: I want to mirror the directory with lftp, and lftp can not read the given filesize correctly out of the index. So lftp has to make HEAD requests to get the file size for each file. The additional HEAD requests would be not necessary if the index returns the exact file size.

Thank you very much and kind regards