19981889 has 2 divisors, whose sum is σ = 19981890. Its totient is φ = 19981888.

The previous prime is 19981873. The next prime is 19981891. The reversal of 19981889 is 98818991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14691889 + 5290000 = 3833^2 + 2300^2 .

It is an emirp because it is prime and its reverse (98818991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19981889 - 2⁴ = 19981873 is a prime.

It is a Sophie Germain prime.

Together with 19981891, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 19981889.

It is not a weakly prime, because it can be changed into another prime (19981189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9990944 + 9990945.

It is an arithmetic number, because the mean of its divisors is an integer number (9990945).

Almost surely, 2^19981889 is an apocalyptic number.

It is an amenable number.

19981889 is a deficient number, since it is larger than the sum of its proper divisors (1).

19981889 is an equidigital number, since it uses as much as digits as its factorization.

19981889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 53.

The square root of 19981889 is about 4470.1106250293. The cubic root of 19981889 is about 271.3598022193.

The spelling of 19981889 in words is "nineteen million, nine hundred eighty-one thousand, eight hundred eighty-nine".