By default, textbook RSA is **not safe** from a modern point of view. Security definitions like [ciphertext-only attacks (COA)](https://en.wikipedia.org/wiki/Ciphertext-only_attack) are used to describe classical ciphers and not relevant for today's cryptosystems: If any cipher doesn't fullfill the much stronger security-definitions, it is considered broken.

So yes, textbook-RSA is considered broken, because for practical use we require security properties which textbook RSA does not have, e.g. [IND-CPA](https://de.wikipedia.org/wiki/Ciphertext_Indistinguishability).

Therefore: Use RSA with a proper padding-scheme, e.g. RSA-OAEP (for encryption) or RSA-PSS (for digital signatures).