866788526551021 has 2 divisors, whose sum is σ = 866788526551022. Its totient is φ = 866788526551020.

The previous prime is 866788526550943. The next prime is 866788526551159. The reversal of 866788526551021 is 120155625887668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 811718561955625 + 55069964595396 = 28490675^2 + 7420914^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866788526551021 is a prime.

It is a super-2 number, since 2×866788526551021² (a number of 31 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866788526351021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433394263275510 + 433394263275511.

It is an arithmetic number, because the mean of its divisors is an integer number (433394263275511).

Almost surely, 2^{866788526551021} is an apocalyptic number.

It is an amenable number.

866788526551021 is a deficient number, since it is larger than the sum of its proper divisors (1).

866788526551021 is an equidigital number, since it uses as much as digits as its factorization.

866788526551021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 387072000, while the sum is 70.

The spelling of 866788526551021 in words is "eight hundred sixty-six trillion, seven hundred eighty-eight billion, five hundred twenty-six million, five hundred fifty-one thousand, twenty-one".