19989839 has 2 divisors, whose sum is σ = 19989840. Its totient is φ = 19989838.

The previous prime is 19989817. The next prime is 19989859. The reversal of 19989839 is 93898991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19989839 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19989859) 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, 9994919 + 9994920.

It is an arithmetic number, because the mean of its divisors is an integer number (9994920).

Almost surely, 2^19989839 is an apocalyptic number.

19989839 is a deficient number, since it is larger than the sum of its proper divisors (1).

19989839 is an equidigital number, since it uses as much as digits as its factorization.

19989839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 56.

The square root of 19989839 is about 4470.9997763364. Note that the first 3 decimals coincide. The cubic root of 19989839 is about 271.3957852102.

The spelling of 19989839 in words is "nineteen million, nine hundred eighty-nine thousand, eight hundred thirty-nine".