18447809 has 2 divisors, whose sum is σ = 18447810. Its totient is φ = 18447808.

The previous prime is 18447797. The next prime is 18447823. The reversal of 18447809 is 90874481.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18447025 + 784 = 4295^2 + 28^2 .

It is an emirp because it is prime and its reverse (90874481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18447809 - 2¹² = 18443713 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18447899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9223904 + 9223905.

It is an arithmetic number, because the mean of its divisors is an integer number (9223905).

Almost surely, 2^18447809 is an apocalyptic number.

It is an amenable number.

18447809 is a deficient number, since it is larger than the sum of its proper divisors (1).

18447809 is an equidigital number, since it uses as much as digits as its factorization.

18447809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64512, while the sum is 41.

The square root of 18447809 is about 4295.0912679476. The cubic root of 18447809 is about 264.2296794068.

The spelling of 18447809 in words is "eighteen million, four hundred forty-seven thousand, eight hundred nine".