12781730681 has 4 divisors (see below), whose sum is σ = 12784634100. Its totient is φ = 12778827264.

The previous prime is 12781730671. The next prime is 12781730713. The reversal of 12781730681 is 18603718721.

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 2271380281 + 10510350400 = 47659^2 + 102520^2 .

It is a cyclic number.

It is not a de Polignac number, because 12781730681 - 2⁶ = 12781730617 is a prime.

It is a super-2 number, since 2×12781730681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12781730641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1445096 + ... + 1453913.

It is an arithmetic number, because the mean of its divisors is an integer number (3196158525).

Almost surely, 2^12781730681 is an apocalyptic number.

It is an amenable number.

12781730681 is a deficient number, since it is larger than the sum of its proper divisors (2903419).

12781730681 is an equidigital number, since it uses as much as digits as its factorization.

12781730681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2903418.

The product of its (nonzero) digits is 112896, while the sum is 44.

The spelling of 12781730681 in words is "twelve billion, seven hundred eighty-one million, seven hundred thirty thousand, six hundred eighty-one".