16805909 has 4 divisors (see below), whose sum is σ = 16859916. Its totient is φ = 16751904.

The previous prime is 16805903. The next prime is 16805933. The reversal of 16805909 is 90950861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90950861 = 2753 ⋅33037.

It can be written as a sum of positive squares in 2 ways, for example, as 1203409 + 15602500 = 1097^2 + 3950^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16805909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16805903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26534 + ... + 27159.

It is an arithmetic number, because the mean of its divisors is an integer number (4214979).

Almost surely, 2^16805909 is an apocalyptic number.

It is an amenable number.

16805909 is a deficient number, since it is larger than the sum of its proper divisors (54007).

16805909 is an equidigital number, since it uses as much as digits as its factorization.

16805909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54006.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 16805909 is about 4099.5010672032. The cubic root of 16805909 is about 256.1458570264.

The spelling of 16805909 in words is "sixteen million, eight hundred five thousand, nine hundred nine".