685390529 has 2 divisors, whose sum is σ = 685390530. Its totient is φ = 685390528.

The previous prime is 685390507. The next prime is 685390543. The reversal of 685390529 is 925093586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 627402304 + 57988225 = 25048^2 + 7615^2 .

It is a cyclic number.

It is not a de Polignac number, because 685390529 - 2⁸ = 685390273 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (685390579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342695264 + 342695265.

It is an arithmetic number, because the mean of its divisors is an integer number (342695265).

Almost surely, 2^685390529 is an apocalyptic number.

It is an amenable number.

685390529 is a deficient number, since it is larger than the sum of its proper divisors (1).

685390529 is an equidigital number, since it uses as much as digits as its factorization.

685390529 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 583200, while the sum is 47.

The square root of 685390529 is about 26179.9642665914. The cubic root of 685390529 is about 881.6834720483.

The spelling of 685390529 in words is "six hundred eighty-five million, three hundred ninety thousand, five hundred twenty-nine".