685748309 has 2 divisors, whose sum is σ = 685748310. Its totient is φ = 685748308.

The previous prime is 685748279. The next prime is 685748333. The reversal of 685748309 is 903847586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 683979409 + 1768900 = 26153^2 + 1330^2 .

It is a cyclic number.

It is not a de Polignac number, because 685748309 - 2²⁸ = 417312853 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685748509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342874154 + 342874155.

It is an arithmetic number, because the mean of its divisors is an integer number (342874155).

Almost surely, 2^685748309 is an apocalyptic number.

It is an amenable number.

685748309 is a deficient number, since it is larger than the sum of its proper divisors (1).

685748309 is an equidigital number, since it uses as much as digits as its factorization.

685748309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1451520, while the sum is 50.

The square root of 685748309 is about 26186.7964631033. The cubic root of 685748309 is about 881.8368609199.

The spelling of 685748309 in words is "six hundred eighty-five million, seven hundred forty-eight thousand, three hundred nine".