686624321 has 2 divisors, whose sum is σ = 686624322. Its totient is φ = 686624320.

The previous prime is 686624303. The next prime is 686624347. The reversal of 686624321 is 123426686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 681784321 + 4840000 = 26111^2 + 2200^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686624321 is a prime.

It is a super-2 number, since 2×686624321² = 942905916377422082, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (686624021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343312160 + 343312161.

It is an arithmetic number, because the mean of its divisors is an integer number (343312161).

Almost surely, 2^686624321 is an apocalyptic number.

It is an amenable number.

686624321 is a deficient number, since it is larger than the sum of its proper divisors (1).

686624321 is an equidigital number, since it uses as much as digits as its factorization.

686624321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 38.

The square root of 686624321 is about 26203.5173402351. The cubic root of 686624321 is about 882.2122031803.

The spelling of 686624321 in words is "six hundred eighty-six million, six hundred twenty-four thousand, three hundred twenty-one".