Why 1729 is a magic number? Answer Logically.

In the picture given below, can you find out which digit will take place of the question mark?

Spot what is wrong here in below Picture?

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.

What has a ring but no finger?

What jumps when it walks and sits when it stands?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

What is the next shape from answers A, B, C, and D figure?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

What is the next number in this series?

4,12,84,3612....