There's only one very good 'cleaner' program. "Wipe and reload". Every year or two, wipe your device (whether Android, PC, Linux, whatever) and restart from scratch. With modern stuff, it's dead simple and virtually always works fine. Various apps for Android (or iOS or Windows or any other OS ever written) may or may not work. May make things better, may make things worse. Better than a coin toss, but not by much in my opinion. Wipe or 'format', and restart from scratch? 99.999% of the time works perfectly.
Apps like CCleaner do offer one absolute advance, placebo effect. They are almost the TSA of the electronic world.
Some useful security related apps:
KeePass2Android - probably most useful app I've ever used in my life. Plays perfectly with desktop KeePass2 files.
Wifi Analyzer - Useful for seeing what wifi networks are around you and at what strength
KeySync - PGP/GPG key sync utility
Android Privacy Guard - GPG client
CSipSimple - SIP client that can handle encrypted calls (aka a softphone)
Signal - Used to be called Redphone, does secure calls and text
Crypt4All - AES utility
Wolfram Alpha - Of course.
K-9 Mail - Can handle secure email
Any voice recorder widget
TagMe - second best geotag software I've used. Footprints by HTC is much better but only comes with HTC phones, I miss the heck out of it.
Osmand - Offline map utility
Torque - Combine with a cheap $20 Bluetooth OBDII dongle, all kinds of useful telemetry from your car
ANYTHING by Guardian Project
https://guardianproject.info/apps/Orbot - Tor proxy for your phone
ChatSecure - XMPP chat standard
Orweb - secure web browser
Pixelknot - Stenography app
If you want to install an AV on your phone, here's some reviews:
https://www.av-test.org/en/antivirus/mobile-devices/android/january-2016/The testing is not perfect, but it's pretty good. AVs get better or worse. And the free ones are worth as much or more than what you pay for them. But paid ones aren't always worth their cost.