1987889 has 2 divisors, whose sum is σ = 1987890. Its totient is φ = 1987888.

The previous prime is 1987883. The next prime is 1987891. The reversal of 1987889 is 9887891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1960000 + 27889 = 1400^2 + 167^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987889 - 2⁴ = 1987873 is a prime.

It is a Sophie Germain prime.

Together with 1987891, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1987883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993944 + 993945.

It is an arithmetic number, because the mean of its divisors is an integer number (993945).

2^1987889 is an apocalyptic number.

It is an amenable number.

1987889 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987889 is an equidigital number, since it uses as much as digits as its factorization.

1987889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 50.

The square root of 1987889 is about 1409.9251753196. The cubic root of 1987889 is about 125.7372748567.

The spelling of 1987889 in words is "one million, nine hundred eighty-seven thousand, eight hundred eighty-nine".