when i opened safari an apple security warning popped up saying (6) virus detected click ok to start cleaning process and then be sure to upgrade system to latest version on your iphone. is this legit?

no, it's just malicious web popups.

It's a scam... Do this: Settings → Safari then tap to Clear History and Website Data then restart your device.

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support: https://support.apple.com/en-ca/HT204759

These are scams and should be ignored

1. Identify and report phishing emails and other suspicious messages: https://support.apple.com/en-us/HT204759

2. Annual Reminder- Watch out for email Phishing Scams: https://blog.macsales.com/40094-an-annual-reminder-watch-out-for-phishing-scams? utm_source=xlr8yourmac

3. Identifying fraudulent "phishing" email: https://support.apple.com/en-us/HT204759

4. Beware of Browser Pop-Up Tech Support, Phishing Scams: http://blog.macsales.com/29155-beware-of-browser-pop-up-tech-support-phishing-sc ams

5. Phishing & Other Suspicious Emails: http://www.apple.com/legal/more-resources/phishing/

6. Avoid phishing emails, fake 'virus' alerts, phony support calls, & other scams: https://support.apple.com/en-us/HT204759

● If you receive what you believe to be a phishing email that's designed to look like it’s from Apple, please send it to reportphishing@apple.com.

● To report spam or other suspicious emails that you receive in your iCloud.com, me.com, or mac.com Inbox, please send them to abuse@icloud.com.

● To report spam or other suspicious messages that you receive through iMessage, tap Report Junk under the message, or take a screenshot on your iPhone, iPad, iPod touch, or Mac and send it to imessage.spam@apple.com.

● If you receive a suspicious message about your purchase activity in the iTunes Store, App Store, or iBooks Store, contact iTunes Support.

No it is a scam. There are no viruses on iPhones.

No. Hope you didn't do it.