549 has 6 divisors (see below), whose sum is σ = 806. Its totient is φ = 360.

The previous prime is 547. The next prime is 557. The reversal of 549 is 945.

549 is nontrivially palindromic in base 13.

It can be written as a sum of positive squares in only one way, i.e., 324 + 225 = 18^2 + 15^2 .

It is not a de Polignac number, because 549 - 2^{1} = 547 is a prime.

It is a fibodiv number, since the Fibonacci-like sequence with seeds 54 and 9 contains 549 itself.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

549 is a nontrivial repdigit in base 13.

It is a plaindrome in base 11, base 12, base 13, base 15 and base 16.

It is a nialpdrome in base 13.

It is a zygodrome in base 13.

It is a congruent number.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 549.

It is not an unprimeable number, because it can be changed into a prime (541) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22 + ... + 39.

It is an amenable number.

549 is a deficient number, since it is larger than the sum of its proper divisors (257).

549 is a wasteful number, since it uses less digits than its factorization.

549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67 (or 64 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 549 is about 23.4307490277. The cubic root of 549 is about 8.1882441101.

Adding to 549 its product of digits (180), we get a 6-th power (729 = 3^{6}).

The spelling of 549 in words is "five hundred forty-nine", and thus it is an aban number.

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