866719661 has 2 divisors, whose sum is σ = 866719662. Its totient is φ = 866719660.

The previous prime is 866719657. The next prime is 866719697. The reversal of 866719661 is 166917668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 864948100 + 1771561 = 29410^2 + 1331^2 .

It is a cyclic number.

It is not a de Polignac number, because 866719661 - 2² = 866719657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866719631) 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, 433359830 + 433359831.

It is an arithmetic number, because the mean of its divisors is an integer number (433359831).

Almost surely, 2^866719661 is an apocalyptic number.

It is an amenable number.

866719661 is a deficient number, since it is larger than the sum of its proper divisors (1).

866719661 is an equidigital number, since it uses as much as digits as its factorization.

866719661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 50.

The square root of 866719661 is about 29440.1029379994. The cubic root of 866719661 is about 953.4389346102.

The spelling of 866719661 in words is "eight hundred sixty-six million, seven hundred nineteen thousand, six hundred sixty-one".