541

541 is a prime number. It is the 100th prime.

541 is a centered dodecagonal number. It is the 10th hexagonal star number.

5! + 4! + 1 = 145, the reverse of 541. 541 is the only odd number greater than 1 with this property.

541 is the number of orderings of five objects with ties allowed.

541 has a representation as a sum of two squares: 541 = 10² + 21².

541 is the hypotenuse of a primitive Pythagorean triple: 541² = 341² + 420².

541 has the representation 541 = 2⁹ + 29.

Source: Number Gossip