13728397581 has 6 divisors (see below), whose sum is σ = 19829907630. Its totient is φ = 9152265048.

The previous prime is 13728397577. The next prime is 13728397597. The reversal of 13728397581 is 18579382731.

It is a happy number.

13728397581 is a `hidden beast` number, since 1 + 3 + 7 + 28 + 39 + 7 + 581 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7649076681 + 6079320900 = 87459^2 + 77970^2 .

It is not a de Polignac number, because 13728397581 - 2² = 13728397577 is a prime.

It is a super-2 number, since 2×13728397581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13728397511) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 762688746 + ... + 762688763.

It is an arithmetic number, because the mean of its divisors is an integer number (3304984605).

Almost surely, 2^13728397581 is an apocalyptic number.

It is an amenable number.

13728397581 is a deficient number, since it is larger than the sum of its proper divisors (6101510049).

13728397581 is a wasteful number, since it uses less digits than its factorization.

13728397581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1525377515 (or 1525377512 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 54.

The spelling of 13728397581 in words is "thirteen billion, seven hundred twenty-eight million, three hundred ninety-seven thousand, five hundred eighty-one".