18720009 has 72 divisors (see below), whose sum is σ = 36492768. Its totient is φ = 9112320.

The previous prime is 18719983. The next prime is 18720083. The reversal of 18720009 is 90002781.

It is not a de Polignac number, because 18720009 - 2¹¹ = 18717961 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18721009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 82354 + ... + 82580.

It is an arithmetic number, because the mean of its divisors is an integer number (506844).

Almost surely, 2^18720009 is an apocalyptic number.

It is an amenable number.

18720009 is a deficient number, since it is larger than the sum of its proper divisors (17772759).

18720009 is a wasteful number, since it uses less digits than its factorization.

18720009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275 (or 265 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 18720009 is about 4326.6625706195. The cubic root of 18720009 is about 265.5229214041.

It can be divided in two parts, 18 and 720009, that added together give a palindrome (720027).

The spelling of 18720009 in words is "eighteen million, seven hundred twenty thousand, nine".