18987389 has 8 divisors (see below), whose sum is σ = 19550208. Its totient is φ = 18431280.

The previous prime is 18987377. The next prime is 18987391. The reversal of 18987389 is 98378981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18987389 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18987389.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18987359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4379 + ... + 7559.

It is an arithmetic number, because the mean of its divisors is an integer number (2443776).

Almost surely, 2^18987389 is an apocalyptic number.

It is an amenable number.

18987389 is a deficient number, since it is larger than the sum of its proper divisors (562819).

18987389 is a wasteful number, since it uses less digits than its factorization.

18987389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3355.

The product of its digits is 870912, while the sum is 53.

The square root of 18987389 is about 4357.4521225138. The cubic root of 18987389 is about 266.7811145895.

It can be divided in two parts, 189 and 87389, that added together give a palindrome (87578).

The spelling of 18987389 in words is "eighteen million, nine hundred eighty-seven thousand, three hundred eighty-nine".