21798819839 has 4 divisors (see below), whose sum is σ = 21801657456. Its totient is φ = 21795982224.

The previous prime is 21798819821. The next prime is 21798819851. The reversal of 21798819839 is 93891889712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21798819839 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 (21798819859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1407254 + ... + 1422659.

It is an arithmetic number, because the mean of its divisors is an integer number (5450414364).

Almost surely, 2^21798819839 is an apocalyptic number.

21798819839 is a deficient number, since it is larger than the sum of its proper divisors (2837617).

21798819839 is an equidigital number, since it uses as much as digits as its factorization.

21798819839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2837616.

The product of its digits is 15676416, while the sum is 65.

The spelling of 21798819839 in words is "twenty-one billion, seven hundred ninety-eight million, eight hundred nineteen thousand, eight hundred thirty-nine".