By default, textbook RSA is not safe from a modern point of view. Security definitions like ciphertext-only attacks (COA) 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.
Therefore: Use RSA with a proper padding-scheme, e.g. RSA-OAEP (for encryption) or RSA-PSS for digital signatures. Using textbook-RSA is a huge risk.