55509 has 4 divisors (see below), whose sum is σ = 74016. Its totient is φ = 37004.

The previous prime is 55501. The next prime is 55511. The reversal of 55509 is 90555.

55509 is nontrivially palindromic in base 11.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 55509 - 2³ = 55501 is a prime.

It is a D-number.

55509 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55501) 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, 9249 + ... + 9254.

It is an arithmetic number, because the mean of its divisors is an integer number (18504).

2⁵⁵⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

55509 is a deficient number, since it is larger than the sum of its proper divisors (18507).

55509 is a wasteful number, since it uses less digits than its factorization.

55509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18506.

The product of its (nonzero) digits is 1125, while the sum is 24.

The square root of 55509 is about 235.6034804497. The cubic root of 55509 is about 38.1464798783.

The spelling of 55509 in words is "fifty-five thousand, five hundred nine".