685386661 has 2 divisors, whose sum is σ = 685386662. Its totient is φ = 685386660.

The previous prime is 685386641. The next prime is 685386701. The reversal of 685386661 is 166683586.

685386661 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., 685130625 + 256036 = 26175^2 + 506^2 .

It is a cyclic number.

It is not a de Polignac number, because 685386661 - 2²³ = 676998053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685386641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342693330 + 342693331.

It is an arithmetic number, because the mean of its divisors is an integer number (342693331).

Almost surely, 2^685386661 is an apocalyptic number.

It is an amenable number.

685386661 is a deficient number, since it is larger than the sum of its proper divisors (1).

685386661 is an equidigital number, since it uses as much as digits as its factorization.

685386661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1244160, while the sum is 49.

The square root of 685386661 is about 26179.8903932007. The cubic root of 685386661 is about 881.6818134523.

The spelling of 685386661 in words is "six hundred eighty-five million, three hundred eighty-six thousand, six hundred sixty-one".