18208009 has 2 divisors, whose sum is σ = 18208010. Its totient is φ = 18208008.

The previous prime is 18208007. The next prime is 18208013. The reversal of 18208009 is 90080281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14227984 + 3980025 = 3772^2 + 1995^2 .

It is an emirp because it is prime and its reverse (90080281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18208009 - 2¹ = 18208007 is a prime.

Together with 18208007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18208007) 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 as a sum of consecutive naturals, namely, 9104004 + 9104005.

It is an arithmetic number, because the mean of its divisors is an integer number (9104005).

Almost surely, 2^18208009 is an apocalyptic number.

It is an amenable number.

18208009 is a deficient number, since it is larger than the sum of its proper divisors (1).

18208009 is an equidigital number, since it uses as much as digits as its factorization.

18208009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 18208009 is about 4267.0843675747. The cubic root of 18208009 is about 263.0797899655.

The spelling of 18208009 in words is "eighteen million, two hundred eight thousand, nine".