686851961 has 2 divisors, whose sum is σ = 686851962. Its totient is φ = 686851960.

The previous prime is 686851951. The next prime is 686851993. The reversal of 686851961 is 169158686.

686851961 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., 386869561 + 299982400 = 19669^2 + 17320^2 .

It is a cyclic number.

It is not a de Polignac number, because 686851961 - 2²⁶ = 619743097 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (686851951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343425980 + 343425981.

It is an arithmetic number, because the mean of its divisors is an integer number (343425981).

Almost surely, 2^686851961 is an apocalyptic number.

It is an amenable number.

686851961 is a deficient number, since it is larger than the sum of its proper divisors (1).

686851961 is an equidigital number, since it uses as much as digits as its factorization.

686851961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 622080, while the sum is 50.

The square root of 686851961 is about 26207.8606719434. The cubic root of 686851961 is about 882.3096871514.

The spelling of 686851961 in words is "six hundred eighty-six million, eight hundred fifty-one thousand, nine hundred sixty-one".