21653799913 has 4 divisors (see below), whose sum is σ = 21654129028. Its totient is φ = 21653470800.

The previous prime is 21653799911. The next prime is 21653799917. The reversal of 21653799913 is 31999735612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5605217424 + 16048582489 = 74868^2 + 126683^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653799913 - 2¹ = 21653799911 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21653799911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28206 + ... + 210007.

It is an arithmetic number, because the mean of its divisors is an integer number (5413532257).

Almost surely, 2^21653799913 is an apocalyptic number.

It is an amenable number.

21653799913 is a deficient number, since it is larger than the sum of its proper divisors (329115).

21653799913 is an equidigital number, since it uses as much as digits as its factorization.

21653799913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329114.

The product of its digits is 2755620, while the sum is 55.

The spelling of 21653799913 in words is "twenty-one billion, six hundred fifty-three million, seven hundred ninety-nine thousand, nine hundred thirteen".