18871989 has 12 divisors (see below), whose sum is σ = 26731104. Its totient is φ = 11840704.

The previous prime is 18871981. The next prime is 18871999. The reversal of 18871989 is 98917881.

It is not a de Polignac number, because 18871989 - 2³ = 18871981 is a prime.

It is a super-2 number, since 2×18871989² = 712303937632242, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18871981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10017 + ... + 11750.

It is an arithmetic number, because the mean of its divisors is an integer number (2227592).

Almost surely, 2^18871989 is an apocalyptic number.

It is an amenable number.

18871989 is a deficient number, since it is larger than the sum of its proper divisors (7859115).

18871989 is a wasteful number, since it uses less digits than its factorization.

18871989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21804 (or 21787 counting only the distinct ones).

The product of its digits is 290304, while the sum is 51.

The square root of 18871989 is about 4344.1902582645. The cubic root of 18871989 is about 266.2395424489.

The spelling of 18871989 in words is "eighteen million, eight hundred seventy-one thousand, nine hundred eighty-nine".