686321 has 2 divisors, whose sum is σ = 686322. Its totient is φ = 686320.

The previous prime is 686317. The next prime is 686333. The reversal of 686321 is 123686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 474721 + 211600 = 689^2 + 460^2 .

It is a cyclic number.

It is not a de Polignac number, because 686321 - 2² = 686317 is a prime.

It is not a weakly prime, because it can be changed into another prime (680321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343160 + 343161.

It is an arithmetic number, because the mean of its divisors is an integer number (343161).

2⁶⁸⁶³²¹ is an apocalyptic number.

It is an amenable number.

686321 is a deficient number, since it is larger than the sum of its proper divisors (1).

686321 is an equidigital number, since it uses as much as digits as its factorization.

686321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 26.

The square root of 686321 is about 828.4449287671. Note that the first 3 decimals coincide. The cubic root of 686321 is about 88.2082276284.

The spelling of 686321 in words is "six hundred eighty-six thousand, three hundred twenty-one".