18189889 has 2 divisors, whose sum is σ = 18189890. Its totient is φ = 18189888.

The previous prime is 18189883. The next prime is 18189917. The reversal of 18189889 is 98898181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16769025 + 1420864 = 4095^2 + 1192^2 .

It is an emirp because it is prime and its reverse (98898181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18189889 - 2⁹ = 18189377 is a prime.

It is not a weakly prime, because it can be changed into another prime (18189883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9094944 + 9094945.

It is an arithmetic number, because the mean of its divisors is an integer number (9094945).

Almost surely, 2^18189889 is an apocalyptic number.

It is an amenable number.

18189889 is a deficient number, since it is larger than the sum of its proper divisors (1).

18189889 is an equidigital number, since it uses as much as digits as its factorization.

18189889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 52.

The square root of 18189889 is about 4264.9606094312. The cubic root of 18189889 is about 262.9924916052.

The spelling of 18189889 in words is "eighteen million, one hundred eighty-nine thousand, eight hundred eighty-nine".