18909009 has 24 divisors (see below), whose sum is σ = 32859840. Its totient is φ = 10235808.

The previous prime is 18908999. The next prime is 18909017. The reversal of 18909009 is 90090981.

It is not a de Polignac number, because 18909009 - 2⁷ = 18908881 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18909019) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6702 + ... + 9095.

It is an arithmetic number, because the mean of its divisors is an integer number (1369160).

Almost surely, 2^18909009 is an apocalyptic number.

18909009 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

18909009 is a deficient number, since it is larger than the sum of its proper divisors (13950831).

18909009 is a wasteful number, since it uses less digits than its factorization.

18909009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15829 (or 15826 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 18909009 is about 4348.4490338510. The cubic root of 18909009 is about 266.4135172239.

The spelling of 18909009 in words is "eighteen million, nine hundred nine thousand, nine".