13728509 has 2 divisors, whose sum is σ = 13728510. Its totient is φ = 13728508.

The previous prime is 13728479. The next prime is 13728511. The reversal of 13728509 is 90582731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8791225 + 4937284 = 2965^2 + 2222^2 .

It is an emirp because it is prime and its reverse (90582731) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13728509 is a prime.

Together with 13728511, it forms a pair of twin primes.

It is a Chen prime.

It is a zygodrome in base 7.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13728529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6864254 + 6864255.

It is an arithmetic number, because the mean of its divisors is an integer number (6864255).

Almost surely, 2^13728509 is an apocalyptic number.

It is an amenable number.

13728509 is a deficient number, since it is larger than the sum of its proper divisors (1).

13728509 is an equidigital number, since it uses as much as digits as its factorization.

13728509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 13728509 is about 3705.2002644931. The cubic root of 13728509 is about 239.4461127334.

The spelling of 13728509 in words is "thirteen million, seven hundred twenty-eight thousand, five hundred nine".