show only numbers before, within or after the text

I have a long text file like this:

324yellow
34house
black
54532
15m21red56
44dfdsf8sfd23

How can I obtain (Perl - Windows/commandline/singleline) the
following?

1) only the numbers at the beginning before some alpha text, like
this:

324
34
15
44

2) only the numbers within the alpha text, like this:

21
8

3) only the numbers at the end after some alpha text, like this:

56
23

.