866466781 has 2 divisors, whose sum is σ = 866466782. Its totient is φ = 866466780.

The previous prime is 866466751. The next prime is 866466827. The reversal of 866466781 is 187664668.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 847683225 + 18783556 = 29115^2 + 4334^2 .

It is a cyclic number.

It is not a de Polignac number, because 866466781 - 2⁵ = 866466749 is a prime.

It is a super-2 number, since 2×866466781² = 1501529365153003922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866466701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433233390 + 433233391.

It is an arithmetic number, because the mean of its divisors is an integer number (433233391).

Almost surely, 2^866466781 is an apocalyptic number.

It is an amenable number.

866466781 is a deficient number, since it is larger than the sum of its proper divisors (1).

866466781 is an equidigital number, since it uses as much as digits as its factorization.

866466781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2322432, while the sum is 52.

The square root of 866466781 is about 29435.8078027426. The cubic root of 866466781 is about 953.3461983229.

The spelling of 866466781 in words is "eight hundred sixty-six million, four hundred sixty-six thousand, seven hundred eighty-one".