19999839 has 4 divisors (see below), whose sum is σ = 26666456. Its totient is φ = 13333224.

The previous prime is 19999831. The next prime is 19999843. The reversal of 19999839 is 93899991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93899991 = 3 ⋅31299997.

It is not a de Polignac number, because 19999839 - 2³ = 19999831 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19999831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3333304 + ... + 3333309.

It is an arithmetic number, because the mean of its divisors is an integer number (6666614).

Almost surely, 2^19999839 is an apocalyptic number.

19999839 is a deficient number, since it is larger than the sum of its proper divisors (6666617).

19999839 is an equidigital number, since it uses as much as digits as its factorization.

19999839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6666616.

The product of its digits is 1417176, while the sum is 57.

The square root of 19999839 is about 4472.1179546161. The cubic root of 19999839 is about 271.4410332888.

The spelling of 19999839 in words is "nineteen million, nine hundred ninety-nine thousand, eight hundred thirty-nine".