12728712505 has 4 divisors (see below), whose sum is σ = 15274455012. Its totient is φ = 10182970000.

The previous prime is 12728712487. The next prime is 12728712547. The reversal of 12728712505 is 50521782721.

It is a happy number.

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 3306710016 + 9422002489 = 57504^2 + 97067^2 .

It is not a de Polignac number, because 12728712505 - 2⁹ = 12728711993 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1272871246 + ... + 1272871255.

It is an arithmetic number, because the mean of its divisors is an integer number (3818613753).

Almost surely, 2^12728712505 is an apocalyptic number.

It is an amenable number.

12728712505 is a deficient number, since it is larger than the sum of its proper divisors (2545742507).

12728712505 is an equidigital number, since it uses as much as digits as its factorization.

12728712505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2545742506.

The product of its (nonzero) digits is 78400, while the sum is 40.

The spelling of 12728712505 in words is "twelve billion, seven hundred twenty-eight million, seven hundred twelve thousand, five hundred five".