878744738561681 has 2 divisors, whose sum is σ = 878744738561682. Its totient is φ = 878744738561680.

The previous prime is 878744738561639. The next prime is 878744738561693. The reversal of 878744738561681 is 186165837447878.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 868504476160000 + 10240262401681 = 29470400^2 + 3200041^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-878744738561681 is a prime.

It is a super-2 number, since 2×878744738561681² (a number of 31 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 878744738561681.

It is not a weakly prime, because it can be changed into another prime (878744738567681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 439372369280840 + 439372369280841.

It is an arithmetic number, because the mean of its divisors is an integer number (439372369280841).

Almost surely, 2^{878744738561681} is an apocalyptic number.

It is an amenable number.

878744738561681 is a deficient number, since it is larger than the sum of its proper divisors (1).

878744738561681 is an equidigital number, since it uses as much as digits as its factorization.

878744738561681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12138577920, while the sum is 83.

The spelling of 878744738561681 in words is "eight hundred seventy-eight trillion, seven hundred forty-four billion, seven hundred thirty-eight million, five hundred sixty-one thousand, six hundred eighty-one".