16909 has 4 divisors (see below), whose sum is σ = 17404. Its totient is φ = 16416.

The previous prime is 16903. The next prime is 16921. The reversal of 16909 is 90961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90961 = 13 ⋅6997.

It can be written as a sum of positive squares in 2 ways, for example, as 14884 + 2025 = 122^2 + 45^2 .

It is a cyclic number.

It is not a de Polignac number, because 16909 - 2³ = 16901 is a prime.

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

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192 + ... + 265.

It is an arithmetic number, because the mean of its divisors is an integer number (4351).

2¹⁶⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

16909 is a deficient number, since it is larger than the sum of its proper divisors (495).

16909 is an equidigital number, since it uses as much as digits as its factorization.

16909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 16909 is about 130.0346107773. The cubic root of 16909 is about 25.6668540681. Note that the first 3 decimals are identical.

The spelling of 16909 in words is "sixteen thousand, nine hundred nine".