685217999 has 2 divisors, whose sum is σ = 685218000. Its totient is φ = 685217998.

The previous prime is 685217971. The next prime is 685218041. The reversal of 685217999 is 999712586.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 685217999 - 2²⁸ = 416782543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685217399) 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, 342608999 + 342609000.

It is an arithmetic number, because the mean of its divisors is an integer number (342609000).

Almost surely, 2^685217999 is an apocalyptic number.

685217999 is a deficient number, since it is larger than the sum of its proper divisors (1).

685217999 is an equidigital number, since it uses as much as digits as its factorization.

685217999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 56.

The square root of 685217999 is about 26176.6689821299. The cubic root of 685217999 is about 881.6094852196.

The spelling of 685217999 in words is "six hundred eighty-five million, two hundred seventeen thousand, nine hundred ninety-nine".