685078321 has 2 divisors, whose sum is σ = 685078322. Its totient is φ = 685078320.

The previous prime is 685078181. The next prime is 685078333. The reversal of 685078321 is 123870586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 648415296 + 36663025 = 25464^2 + 6055^2 .

It is a cyclic number.

It is not a de Polignac number, because 685078321 - 2¹³ = 685070129 is a prime.

It is not a weakly prime, because it can be changed into another prime (685078351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342539160 + 342539161.

It is an arithmetic number, because the mean of its divisors is an integer number (342539161).

Almost surely, 2^685078321 is an apocalyptic number.

It is an amenable number.

685078321 is a deficient number, since it is larger than the sum of its proper divisors (1).

685078321 is an equidigital number, since it uses as much as digits as its factorization.

685078321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80640, while the sum is 40.

The square root of 685078321 is about 26174.0008596317. Note that the first 3 decimals coincide. The cubic root of 685078321 is about 881.5495773664.

The spelling of 685078321 in words is "six hundred eighty-five million, seventy-eight thousand, three hundred twenty-one".