18009841 has 4 divisors (see below), whose sum is σ = 18630900. Its totient is φ = 17388784.

The previous prime is 18009833. The next prime is 18009857. The reversal of 18009841 is 14890081.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6477025 + 11532816 = 2545^2 + 3396^2 .

It is a cyclic number.

It is not a de Polignac number, because 18009841 - 2³ = 18009833 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18009821) 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 in 3 ways as a sum of consecutive naturals, for example, 310486 + ... + 310543.

It is an arithmetic number, because the mean of its divisors is an integer number (4657725).

Almost surely, 2^18009841 is an apocalyptic number.

It is an amenable number.

18009841 is a deficient number, since it is larger than the sum of its proper divisors (621059).

18009841 is an equidigital number, since it uses as much as digits as its factorization.

18009841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 621058.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 18009841 is about 4243.8003016165. The cubic root of 18009841 is about 262.1218913049.

The spelling of 18009841 in words is "eighteen million, nine thousand, eight hundred forty-one".