866868661 has 2 divisors, whose sum is σ = 866868662. Its totient is φ = 866868660.

The previous prime is 866868647. The next prime is 866868679. The reversal of 866868661 is 166868668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 652802500 + 214066161 = 25550^2 + 14631^2 .

It is a cyclic number.

It is not a de Polignac number, because 866868661 - 2²³ = 858480053 is a prime.

It is a super-2 number, since 2×866868661² = 1502922550847865842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866868631) 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, 433434330 + 433434331.

It is an arithmetic number, because the mean of its divisors is an integer number (433434331).

Almost surely, 2^866868661 is an apocalyptic number.

It is an amenable number.

866868661 is a deficient number, since it is larger than the sum of its proper divisors (1).

866868661 is an equidigital number, since it uses as much as digits as its factorization.

866868661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3981312, while the sum is 55.

The square root of 866868661 is about 29442.6333910539. The cubic root of 866868661 is about 953.4935675239.

The spelling of 866868661 in words is "eight hundred sixty-six million, eight hundred sixty-eight thousand, six hundred sixty-one".