866965661 has 2 divisors, whose sum is σ = 866965662. Its totient is φ = 866965660.

The previous prime is 866965639. The next prime is 866965663. The reversal of 866965661 is 166569668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 560505625 + 306460036 = 23675^2 + 17506^2 .

It is a cyclic number.

It is not a de Polignac number, because 866965661 - 2¹⁴ = 866949277 is a prime.

Together with 866965663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866965663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433482830 + 433482831.

It is an arithmetic number, because the mean of its divisors is an integer number (433482831).

Almost surely, 2^866965661 is an apocalyptic number.

It is an amenable number.

866965661 is a deficient number, since it is larger than the sum of its proper divisors (1).

866965661 is an equidigital number, since it uses as much as digits as its factorization.

866965661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2799360, while the sum is 53.

The square root of 866965661 is about 29444.2806161061. The cubic root of 866965661 is about 953.5291305531.

The spelling of 866965661 in words is "eight hundred sixty-six million, nine hundred sixty-five thousand, six hundred sixty-one".