685824342821 has 2 divisors, whose sum is σ = 685824342822. Its totient is φ = 685824342820.

The previous prime is 685824342809. The next prime is 685824342839. The reversal of 685824342821 is 128243428586.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 390637500100 + 295186842721 = 625010^2 + 543311^2 .

It is a cyclic number.

It is not a de Polignac number, because 685824342821 - 2³⁰ = 684750600997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685824342881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342912171410 + 342912171411.

It is an arithmetic number, because the mean of its divisors is an integer number (342912171411).

Almost surely, 2^685824342821 is an apocalyptic number.

It is an amenable number.

685824342821 is a deficient number, since it is larger than the sum of its proper divisors (1).

685824342821 is an equidigital number, since it uses as much as digits as its factorization.

685824342821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5898240, while the sum is 53.

The spelling of 685824342821 in words is "six hundred eighty-five billion, eight hundred twenty-four million, three hundred forty-two thousand, eight hundred twenty-one".