Learn Spanish (Latin America): El cuarto está sucio, yo mismo necesito la aspiradora ahora mismo. - The room is dirty, I myself need the vacuum cleaner right now.

Adding mismo to a subject pronoun emphasizes exactly who is involved, translating to 'I myself' in English. Because it describes the speaker here, it must agree with their gender. If the speaker were a woman, she would say yo misma.

Does mismo in ahora mismo change for gender or number like it does in yo mismo?

No, it doesn't. When mismo attaches to a time or place word like ahora (now) to add emphasis (meaning 'right now'), it acts as an adverb. Since adverbs never change for gender or number, it will always be ahora mismo regardless of who is speaking or what is being discussed.

Why does the sentence use está instead of es for 'is dirty'?

We use está (from the verb estar) because being dirty is a temporary physical condition or state. If you used es (from the verb ser), it would sound like being dirty is a permanent, defining characteristic of the room.

Is there a difference between el cuarto and la habitación?