685125909 has 48 divisors (see below), whose sum is σ = 1135959552. Its totient is φ = 394631424.

The previous prime is 685125871. The next prime is 685125911. The reversal of 685125909 is 909521586.

685125909 is a `hidden beast` number, since 6 + 8 + 51 + 2 + 590 + 9 = 666.

It is not a de Polignac number, because 685125909 - 2¹⁵ = 685093141 is a prime.

It is a super-2 number, since 2×685125909² = 938795022366152562, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685125979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 123769 + ... + 129185.

It is an arithmetic number, because the mean of its divisors is an integer number (23665824).

Almost surely, 2^685125909 is an apocalyptic number.

685125909 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

It is an amenable number.

685125909 is a deficient number, since it is larger than the sum of its proper divisors (450833643).

685125909 is a wasteful number, since it uses less digits than its factorization.

685125909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5506 (or 5503 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The square root of 685125909 is about 26174.9099138851. The cubic root of 685125909 is about 881.5699887601.

The spelling of 685125909 in words is "six hundred eighty-five million, one hundred twenty-five thousand, nine hundred nine".