12781894385 has 36 divisors (see below), whose sum is σ = 17021553948. Its totient is φ = 9159599232.

The previous prime is 12781894373. The next prime is 12781894387. The reversal of 12781894385 is 58349818721.

It can be written as a sum of positive squares in 6 ways, for example, as 450458176 + 12331436209 = 21224^2 + 111047^2 .

It is not a de Polignac number, because 12781894385 - 2¹⁰ = 12781893361 is a prime.

It is an alternating number because its digits alternate between odd and even.

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 12781894385.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12781894387) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 33725126 + ... + 33725504.

It is an arithmetic number, because the mean of its divisors is an integer number (472820943).

Almost surely, 2^12781894385 is an apocalyptic number.

It is an amenable number.

12781894385 is a deficient number, since it is larger than the sum of its proper divisors (4239659563).

12781894385 is an frugal number, since it uses more digits than its factorization.

12781894385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850 (or 434 counting only the distinct ones).

The product of its digits is 3870720, while the sum is 56.

The spelling of 12781894385 in words is "twelve billion, seven hundred eighty-one million, eight hundred ninety-four thousand, three hundred eighty-five".