861166681 has 2 divisors, whose sum is σ = 861166682. Its totient is φ = 861166680.

The previous prime is 861166661. The next prime is 861166711. The reversal of 861166681 is 186661168.

861166681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 430977600 + 430189081 = 20760^2 + 20741^2 .

It is a cyclic number.

It is not a de Polignac number, because 861166681 - 2⁹ = 861166169 is a prime.

It is a super-2 number, since 2×861166681² = 1483216104929111522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (861166661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430583340 + 430583341.

It is an arithmetic number, because the mean of its divisors is an integer number (430583341).

Almost surely, 2^861166681 is an apocalyptic number.

It is an amenable number.

861166681 is a deficient number, since it is larger than the sum of its proper divisors (1).

861166681 is an equidigital number, since it uses as much as digits as its factorization.

861166681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 43.

The square root of 861166681 is about 29345.6416014372. The cubic root of 861166681 is about 951.3983768093.

The spelling of 861166681 in words is "eight hundred sixty-one million, one hundred sixty-six thousand, six hundred eighty-one".