18917889 has 16 divisors (see below), whose sum is σ = 27630720. Its totient is φ = 11459840.

The previous prime is 18917881. The next prime is 18917897. The reversal of 18917889 is 98871981.

It is an interprime number because it is at equal distance from previous prime (18917881) and next prime (18917897).

It is a cyclic number.

It is not a de Polignac number, because 18917889 - 2³ = 18917881 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (18917881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4917 + ... + 7874.

It is an arithmetic number, because the mean of its divisors is an integer number (1726920).

Almost surely, 2^18917889 is an apocalyptic number.

It is an amenable number.

18917889 is a deficient number, since it is larger than the sum of its proper divisors (8712831).

18917889 is a wasteful number, since it uses less digits than its factorization.

18917889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12840.

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

The square root of 18917889 is about 4349.4699677087. The cubic root of 18917889 is about 266.4552148401.

The spelling of 18917889 in words is "eighteen million, nine hundred seventeen thousand, eight hundred eighty-nine".