18272809 has 2 divisors, whose sum is σ = 18272810. Its totient is φ = 18272808.

The previous prime is 18272803. The next prime is 18272867. The reversal of 18272809 is 90827281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13344409 + 4928400 = 3653^2 + 2220^2 .

It is an emirp because it is prime and its reverse (90827281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18272809 - 2²¹ = 16175657 is a prime.

It is not a weakly prime, because it can be changed into another prime (18272803) 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, 9136404 + 9136405.

It is an arithmetic number, because the mean of its divisors is an integer number (9136405).

Almost surely, 2^18272809 is an apocalyptic number.

It is an amenable number.

18272809 is a deficient number, since it is larger than the sum of its proper divisors (1).

18272809 is an equidigital number, since it uses as much as digits as its factorization.

18272809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 18272809 is about 4274.6706305866. The cubic root of 18272809 is about 263.3915096946.

The spelling of 18272809 in words is "eighteen million, two hundred seventy-two thousand, eight hundred nine".