21705613313 has 4 divisors (see below), whose sum is σ = 21706235220. Its totient is φ = 21704991408.

The previous prime is 21705613261. The next prime is 21705613331. The reversal of 21705613313 is 31331650712.

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 14906456464 + 6799156849 = 122092^2 + 82457^2 .

It is a cyclic number.

It is not a de Polignac number, because 21705613313 - 2²⁴ = 21688836097 is a prime.

It is a super-2 number, since 2×21705613313² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21705613313.

It is not an unprimeable number, because it can be changed into a prime (21705613343) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255278 + ... + 329511.

It is an arithmetic number, because the mean of its divisors is an integer number (5426558805).

Almost surely, 2^21705613313 is an apocalyptic number.

It is an amenable number.

21705613313 is a deficient number, since it is larger than the sum of its proper divisors (621907).

21705613313 is an equidigital number, since it uses as much as digits as its factorization.

21705613313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 621906.

The product of its (nonzero) digits is 11340, while the sum is 32.

The spelling of 21705613313 in words is "twenty-one billion, seven hundred five million, six hundred thirteen thousand, three hundred thirteen".