19878839 has 2 divisors, whose sum is σ = 19878840. Its totient is φ = 19878838.

The previous prime is 19878829. The next prime is 19878841. The reversal of 19878839 is 93887891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19878839 - 2⁴ = 19878823 is a prime.

Together with 19878841, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19878829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9939419 + 9939420.

It is an arithmetic number, because the mean of its divisors is an integer number (9939420).

Almost surely, 2^19878839 is an apocalyptic number.

19878839 is a deficient number, since it is larger than the sum of its proper divisors (1).

19878839 is an equidigital number, since it uses as much as digits as its factorization.

19878839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 53.

The square root of 19878839 is about 4458.5691651022. The cubic root of 19878839 is about 270.8925151194.

The spelling of 19878839 in words is "nineteen million, eight hundred seventy-eight thousand, eight hundred thirty-nine".