549809 has 4 divisors (see below), whose sum is σ = 592116. Its totient is φ = 507504.

The previous prime is 549767. The next prime is 549817. The reversal of 549809 is 908945.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 908945 = 5 ⋅181789.

It can be written as a sum of positive squares in 2 ways, for example, as 107584 + 442225 = 328^2 + 665^2 .

It is a cyclic number.

It is not a de Polignac number, because 549809 - 2⁸ = 549553 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (549839) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21134 + ... + 21159.

It is an arithmetic number, because the mean of its divisors is an integer number (148029).

2⁵⁴⁹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

549809 is a deficient number, since it is larger than the sum of its proper divisors (42307).

549809 is a wasteful number, since it uses less digits than its factorization.

549809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42306.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 549809 is about 741.4910653541. The cubic root of 549809 is about 81.9226416976.

The spelling of 549809 in words is "five hundred forty-nine thousand, eight hundred nine".