685754578609 has 9 divisors (see below), whose sum is σ = 708615805419. Its totient is φ = 663608620080.

The previous prime is 685754578559. The next prime is 685754578633. The reversal of 685754578609 is 906875457586.

The square root of 685754578609 is 828103.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 671047680625 + 14706897984 = 819175^2 + 121272^2 .

It is not a de Polignac number, because 685754578609 - 2¹⁵ = 685754545841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685754572609) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 25657837 + ... + 25684549.

It is an arithmetic number, because the mean of its divisors is an integer number (78735089491).

Almost surely, 2^685754578609 is an apocalyptic number.

685754578609 is the 828103-rd square number.

685754578609 is the 414052-nd centered octagonal number.

It is an amenable number.

685754578609 is a deficient number, since it is larger than the sum of its proper divisors (22861226810).

685754578609 is an frugal number, since it uses more digits than its factorization.

685754578609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53488 (or 26744 counting only the distinct ones).

The product of its (nonzero) digits is 508032000, while the sum is 70.

The spelling of 685754578609 in words is "six hundred eighty-five billion, seven hundred fifty-four million, five hundred seventy-eight thousand, six hundred nine".