12781635905 has 4 divisors (see below), whose sum is σ = 15337963092. Its totient is φ = 10225308720.

The previous prime is 12781635899. The next prime is 12781635931. The reversal of 12781635905 is 50953618721.

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 9026520064 + 3755115841 = 95008^2 + 61279^2 .

It is not a de Polignac number, because 12781635905 - 2⁸ = 12781635649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12781635905.

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, 1278163586 + ... + 1278163595.

It is an arithmetic number, because the mean of its divisors is an integer number (3834490773).

Almost surely, 2^12781635905 is an apocalyptic number.

It is an amenable number.

12781635905 is a deficient number, since it is larger than the sum of its proper divisors (2556327187).

12781635905 is an equidigital number, since it uses as much as digits as its factorization.

12781635905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2556327186.

The product of its (nonzero) digits is 453600, while the sum is 47.

The spelling of 12781635905 in words is "twelve billion, seven hundred eighty-one million, six hundred thirty-five thousand, nine hundred five".