You can definitely export .numbers spreadsheets as PDF documents in the default Numbers app for macOS and iOS. If you do not have access to any of the Apple devices, you can use a workaround using iWork for iCloud accessible through web browser.
Some later versions of LibreOffice Calc can open (and thus export to PDF) some earlier versions of Numbers spreadsheets, but this may not work well for some of the latest versions of the format.Open NUMBERS file Open PDF file
An on-line version of Pages, Numbers, and Keynote
Full-featured spreadsheet tool from LibreOffice suite
A preadsheet editing application for iOS
A spreadsheet application from Apple