685143509 has 2 divisors, whose sum is σ = 685143510. Its totient is φ = 685143508.

The previous prime is 685143457. The next prime is 685143517. The reversal of 685143509 is 905341586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 681732100 + 3411409 = 26110^2 + 1847^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685143509 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685143409) 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, 342571754 + 342571755.

It is an arithmetic number, because the mean of its divisors is an integer number (342571755).

Almost surely, 2^685143509 is an apocalyptic number.

It is an amenable number.

685143509 is a deficient number, since it is larger than the sum of its proper divisors (1).

685143509 is an equidigital number, since it uses as much as digits as its factorization.

685143509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129600, while the sum is 41.

The square root of 685143509 is about 26175.2461115459. The cubic root of 685143509 is about 881.5775374937.

The spelling of 685143509 in words is "six hundred eighty-five million, one hundred forty-three thousand, five hundred nine".