18143281809 has 27 divisors (see below), whose sum is σ = 26693754139.
Its totient is φ = 11874887520.
The previous prime is 18143281781. The next prime is 18143281837. The reversal of 18143281809 is 90818234181.
The square root of 18143281809 is 134697.
It is a perfect power (a square), and thus also a powerful number.
It is an interprime number because it is at equal distance from previous prime (18143281781) and next prime (18143281837).
It can be written as a sum of positive squares in only one way, i.e., 47651409 + 18095630400 = 6903^2 + 134520^2
It is not a de Polignac number, because 18143281809 - 229 = 17606410897 is a prime.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (18143281879) by changing a digit.
It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 23840989 + ... + 23841749.
Almost surely, 218143281809 is an apocalyptic number.
18143281809 is the 134697-th square number.
18143281809 is the 67349-th centered octagonal number.
It is an amenable number.
18143281809 is a deficient number, since it is larger than the sum of its proper divisors (8550472330).
18143281809 is an frugal number, since it uses more digits than its factorization.
18143281809 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1646 (or 823 counting only the distinct ones).
The product of its (nonzero) digits is 110592, while the sum is 45.
The spelling of 18143281809 in words is "eighteen billion, one hundred forty-three million, two hundred eighty-one thousand, eight hundred nine".