18311209 has 8 divisors (see below), whose sum is σ = 21648960. Its totient is φ = 15153936.

The previous prime is 18311207. The next prime is 18311219. The reversal of 18311209 is 90211381.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18311209 - 2¹ = 18311207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18311201) 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 7 ways as a sum of consecutive naturals, for example, 44899 + ... + 45304.

It is an arithmetic number, because the mean of its divisors is an integer number (2706120).

Almost surely, 2^18311209 is an apocalyptic number.

It is an amenable number.

18311209 is a deficient number, since it is larger than the sum of its proper divisors (3337751).

18311209 is an equidigital number, since it uses as much as digits as its factorization.

18311209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90239.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 18311209 is about 4279.1598474467. The cubic root of 18311209 is about 263.5758848732.

The spelling of 18311209 in words is "eighteen million, three hundred eleven thousand, two hundred nine".