199981889 has 2 divisors, whose sum is σ = 199981890. Its totient is φ = 199981888.

The previous prime is 199981871. The next prime is 199981891. The reversal of 199981889 is 988189991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180445489 + 19536400 = 13433^2 + 4420^2 .

It is a cyclic number.

It is not a de Polignac number, because 199981889 - 2²⁴ = 183204673 is a prime.

It is a Sophie Germain prime.

Together with 199981891, 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 (199981819) 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 as a sum of consecutive naturals, namely, 99990944 + 99990945.

It is an arithmetic number, because the mean of its divisors is an integer number (99990945).

Almost surely, 2^199981889 is an apocalyptic number.

It is an amenable number.

199981889 is a deficient number, since it is larger than the sum of its proper divisors (1).

199981889 is an equidigital number, since it uses as much as digits as its factorization.

199981889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3359232, while the sum is 62.

The square root of 199981889 is about 14141.4952886885. The cubic root of 199981889 is about 584.7858948146.

The spelling of 199981889 in words is "one hundred ninety-nine million, nine hundred eighty-one thousand, eight hundred eighty-nine".