19721361197 has 4 divisors (see below), whose sum is σ = 19721643996. Its totient is φ = 19721078400.

The previous prime is 19721361167. The next prime is 19721361211. The reversal of 19721361197 is 79116312791.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10954971556 + 8766389641 = 104666^2 + 93629^2 .

It is a cyclic number.

It is not a de Polignac number, because 19721361197 - 2⁶ = 19721361133 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 (19721361137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45947 + ... + 203847.

It is an arithmetic number, because the mean of its divisors is an integer number (4930410999).

Almost surely, 2^19721361197 is an apocalyptic number.

It is an amenable number.

19721361197 is a deficient number, since it is larger than the sum of its proper divisors (282799).

19721361197 is a wasteful number, since it uses less digits than its factorization.

19721361197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 282798.

The product of its digits is 142884, while the sum is 47.

The spelling of 19721361197 in words is "nineteen billion, seven hundred twenty-one million, three hundred sixty-one thousand, one hundred ninety-seven".