13531944721 has 2 divisors, whose sum is σ = 13531944722. Its totient is φ = 13531944720.

The previous prime is 13531944719. The next prime is 13531944749. The reversal of 13531944721 is 12744913531.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9093720321 + 4438224400 = 95361^2 + 66620^2 .

It is a cyclic number.

It is not a de Polignac number, because 13531944721 - 2¹ = 13531944719 is a prime.

It is a super-2 number, since 2×13531944721² (a number of 21 digits) contains 22 as substring.

Together with 13531944719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (13531944421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6765972360 + 6765972361.

It is an arithmetic number, because the mean of its divisors is an integer number (6765972361).

Almost surely, 2^13531944721 is an apocalyptic number.

It is an amenable number.

13531944721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13531944721 is an equidigital number, since it uses as much as digits as its factorization.

13531944721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 40.

The spelling of 13531944721 in words is "thirteen billion, five hundred thirty-one million, nine hundred forty-four thousand, seven hundred twenty-one".