top (table of processes) package on Ubuntu 16.04 LTS

When I run sudo apt install top, I get E: Unable to locate package top

I searched packages.ubuntu.com for top package on 32 bit Ubuntu 16.04 LTS, but there is none.

I wonder if it's correct or I'm missing something.

It is probably installed with the procps package. It is also common in all *NIX OSes. If you really need to find what it is installed with, install apt-file first:

sudo apt install apt-file && apt-file update

If you run a which command it will return the folder that it is installed into:

$ which top
/usr/bin/top

Then do a search like this:

apt-file search --regexp '/top$'

It will return a list like this:

broctl: /usr/share/broctl/scripts/helpers/top
crossfire-maps: /usr/share/games/crossfire/maps/santo_dominion/magara/well/top

crossfire-maps-small: /usr/share/games/crossfire/maps/santo_dominion/magara/well/top
liece: /usr/share/emacs/site-lisp/liece/styles/top
lubuntu-extra-sessions: /usr/share/lxpanel/profile/Lubuntu-Nexus7/panels/top
lxpanel: /etc/xdg/lxpanel/two_panels/panels/top
procps: /usr/bin/top
quilt: /usr/share/quilt/top
trn4: /usr/share/doc/trn4/examples/univ/top
trn4: /usr/share/trn4/HelpFiles/top

Then all you have to do is match the folder, and that is the package at the beginning of the line.

Or, you could combine the statement as one and it should return a more exact result:

$ apt-file search --regexp $(which top)$
procps: /usr/bin/top

Hope this helps!