19821328399 has 4 divisors (see below), whose sum is σ = 19861051000. Its totient is φ = 19781605800.

The previous prime is 19821328393. The next prime is 19821328427. The reversal of 19821328399 is 99382312891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19821328399 - 2¹⁹ = 19820804111 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 (19821328393) 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, 19860552 + ... + 19861549.

It is an arithmetic number, because the mean of its divisors is an integer number (4965262750).

Almost surely, 2^19821328399 is an apocalyptic number.

19821328399 is a deficient number, since it is larger than the sum of its proper divisors (39722601).

19821328399 is an equidigital number, since it uses as much as digits as its factorization.

19821328399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39722600.

The product of its digits is 1679616, while the sum is 55.

The spelling of 19821328399 in words is "nineteen billion, eight hundred twenty-one million, three hundred twenty-eight thousand, three hundred ninety-nine".