12191819221 has 4 divisors (see below), whose sum is σ = 12585103744. Its totient is φ = 11798534700.

The previous prime is 12191819209. The next prime is 12191819251. The reversal of 12191819221 is 12291819121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12191819221 - 2¹⁹ = 12191294933 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 (12191819251) 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, 196642215 + ... + 196642276.

It is an arithmetic number, because the mean of its divisors is an integer number (3146275936).

Almost surely, 2^12191819221 is an apocalyptic number.

It is an amenable number.

12191819221 is a deficient number, since it is larger than the sum of its proper divisors (393284523).

12191819221 is an equidigital number, since it uses as much as digits as its factorization.

12191819221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393284522.

The product of its digits is 5184, while the sum is 37.

The spelling of 12191819221 in words is "twelve billion, one hundred ninety-one million, eight hundred nineteen thousand, two hundred twenty-one".