19660838399 has 4 divisors (see below), whose sum is σ = 19684555560. Its totient is φ = 19637121240.

The previous prime is 19660838303. The next prime is 19660838401. The reversal of 19660838399 is 99383806691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99383806691 = 13 ⋅7644908207.

It is a cyclic number.

It is not a de Polignac number, because 19660838399 - 2⁸ = 19660838143 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 (19660838299) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11857337 + ... + 11858994.

It is an arithmetic number, because the mean of its divisors is an integer number (4921138890).

Almost surely, 2^19660838399 is an apocalyptic number.

19660838399 is a deficient number, since it is larger than the sum of its proper divisors (23717161).

19660838399 is an equidigital number, since it uses as much as digits as its factorization.

19660838399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23717160.

The product of its (nonzero) digits is 15116544, while the sum is 62.

The spelling of 19660838399 in words is "nineteen billion, six hundred sixty million, eight hundred thirty-eight thousand, three hundred ninety-nine".