18871889 has 2 divisors, whose sum is σ = 18871890. Its totient is φ = 18871888.

The previous prime is 18871873. The next prime is 18871903. The reversal of 18871889 is 98817881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 1399489 = 4180^2 + 1183^2 .

It is a cyclic number.

It is not a de Polignac number, because 18871889 - 2⁴ = 18871873 is a prime.

It is a super-2 number, since 2×18871889² = 712296388856642, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18871859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9435944 + 9435945.

It is an arithmetic number, because the mean of its divisors is an integer number (9435945).

Almost surely, 2^18871889 is an apocalyptic number.

It is an amenable number.

18871889 is a deficient number, since it is larger than the sum of its proper divisors (1).

18871889 is an equidigital number, since it uses as much as digits as its factorization.

18871889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 258048, while the sum is 50.

The square root of 18871889 is about 4344.1787486244. The cubic root of 18871889 is about 266.2390721929.

The spelling of 18871889 in words is "eighteen million, eight hundred seventy-one thousand, eight hundred eighty-nine".