685220700509 has 2 divisors, whose sum is σ = 685220700510. Its totient is φ = 685220700508.

The previous prime is 685220700469. The next prime is 685220700523. The reversal of 685220700509 is 905007022586.

685220700509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 640965163609 + 44255536900 = 800603^2 + 210370^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685220700509 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 685220700509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685220700569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342610350254 + 342610350255.

It is an arithmetic number, because the mean of its divisors is an integer number (342610350255).

Almost surely, 2^685220700509 is an apocalyptic number.

It is an amenable number.

685220700509 is a deficient number, since it is larger than the sum of its proper divisors (1).

685220700509 is an equidigital number, since it uses as much as digits as its factorization.

685220700509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 302400, while the sum is 44.

The spelling of 685220700509 in words is "six hundred eighty-five billion, two hundred twenty million, seven hundred thousand, five hundred nine".