686665169 has 2 divisors, whose sum is σ = 686665170. Its totient is φ = 686665168.

The previous prime is 686665157. The next prime is 686665183. The reversal of 686665169 is 961566686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 411602944 + 275062225 = 20288^2 + 16585^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686665169 is a prime.

It is a super-2 number, since 2×686665169² = 943018108635597122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 686665169.

It is not a weakly prime, because it can be changed into another prime (686665769) 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, 343332584 + 343332585.

It is an arithmetic number, because the mean of its divisors is an integer number (343332585).

Almost surely, 2^686665169 is an apocalyptic number.

It is an amenable number.

686665169 is a deficient number, since it is larger than the sum of its proper divisors (1).

686665169 is an equidigital number, since it uses as much as digits as its factorization.

686665169 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 686665169 is about 26204.2967659886. The cubic root of 686665169 is about 882.2296974094.

The spelling of 686665169 in words is "six hundred eighty-six million, six hundred sixty-five thousand, one hundred sixty-nine".