18787989 has 16 divisors (see below), whose sum is σ = 27639360. Its totient is φ = 11256960.

The previous prime is 18787943. The next prime is 18787991. The reversal of 18787989 is 98978781.

It is not a de Polignac number, because 18787989 - 2⁹ = 18787477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18787289) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 262 + ... + 6135.

It is an arithmetic number, because the mean of its divisors is an integer number (1727460).

Almost surely, 2^18787989 is an apocalyptic number.

It is an amenable number.

18787989 is a deficient number, since it is larger than the sum of its proper divisors (8851371).

18787989 is a wasteful number, since it uses less digits than its factorization.

18787989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6500.

The product of its digits is 2032128, while the sum is 57.

The square root of 18787989 is about 4334.5113911489. The cubic root of 18787989 is about 265.8439405321.

The spelling of 18787989 in words is "eighteen million, seven hundred eighty-seven thousand, nine hundred eighty-nine".