18916009 has 6 divisors (see below), whose sum is σ = 22004394. Its totient is φ = 16213680.

The previous prime is 18915989. The next prime is 18916031. The reversal of 18916009 is 90061981.

It can be written as a sum of positive squares in only one way, i.e., 18896409 + 19600 = 4347^2 + 140^2 .

It is not a de Polignac number, because 18916009 - 2⁹ = 18915497 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 (18916099) 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, 192972 + ... + 193069.

It is an arithmetic number, because the mean of its divisors is an integer number (3667399).

Almost surely, 2^18916009 is an apocalyptic number.

It is an amenable number.

18916009 is a deficient number, since it is larger than the sum of its proper divisors (3088385).

18916009 is an equidigital number, since it uses as much as digits as its factorization.

18916009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386055 (or 386048 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 18916009 is about 4349.2538440519. The cubic root of 18916009 is about 266.4463880554.

The spelling of 18916009 in words is "eighteen million, nine hundred sixteen thousand, nine".