19819889 has 2 divisors, whose sum is σ = 19819890. Its totient is φ = 19819888.

The previous prime is 19819883. The next prime is 19819897. The reversal of 19819889 is 98891891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15054400 + 4765489 = 3880^2 + 2183^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19819889 is a prime.

It is a Sophie Germain 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 19819889.

It is not a weakly prime, because it can be changed into another prime (19819883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9909944 + 9909945.

It is an arithmetic number, because the mean of its divisors is an integer number (9909945).

Almost surely, 2^19819889 is an apocalyptic number.

It is an amenable number.

19819889 is a deficient number, since it is larger than the sum of its proper divisors (1).

19819889 is an equidigital number, since it uses as much as digits as its factorization.

19819889 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 19819889 is about 4451.9533914901. The cubic root of 19819889 is about 270.6244759060.

The spelling of 19819889 in words is "nineteen million, eight hundred nineteen thousand, eight hundred eighty-nine".