13813257721 has 4 divisors (see below), whose sum is σ = 13889574244. Its totient is φ = 13736941200.

The previous prime is 13813257631. The next prime is 13813257737. The reversal of 13813257721 is 12775231831.

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 179426025 + 13633831696 = 13395^2 + 116764^2 .

It is a cyclic number.

It is not a de Polignac number, because 13813257721 - 2⁷ = 13813257593 is a prime.

It is a super-2 number, since 2×13813257721² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13813257761) 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, 38157990 + ... + 38158351.

It is an arithmetic number, because the mean of its divisors is an integer number (3472393561).

Almost surely, 2^13813257721 is an apocalyptic number.

It is an amenable number.

13813257721 is a deficient number, since it is larger than the sum of its proper divisors (76316523).

13813257721 is an equidigital number, since it uses as much as digits as its factorization.

13813257721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76316522.

The product of its digits is 70560, while the sum is 40.

The spelling of 13813257721 in words is "thirteen billion, eight hundred thirteen million, two hundred fifty-seven thousand, seven hundred twenty-one".