18987808189 has 4 divisors (see below), whose sum is σ = 21700352224. Its totient is φ = 16275264156.

The previous prime is 18987808129. The next prime is 18987808207. The reversal of 18987808189 is 98180878981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 98180878981 = 109 ⋅900742009.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18987808189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18987808129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1356272007 + ... + 1356272020.

It is an arithmetic number, because the mean of its divisors is an integer number (5425088056).

Almost surely, 2^18987808189 is an apocalyptic number.

It is an amenable number.

18987808189 is a deficient number, since it is larger than the sum of its proper divisors (2712544035).

18987808189 is an equidigital number, since it uses as much as digits as its factorization.

18987808189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2712544034.

The product of its (nonzero) digits is 18579456, while the sum is 67.

The spelling of 18987808189 in words is "eighteen billion, nine hundred eighty-seven million, eight hundred eight thousand, one hundred eighty-nine".