681785 has 16 divisors (see below), whose sum is σ = 934416. Its totient is φ = 473088.

The previous prime is 681781. The next prime is 681787. The reversal of 681785 is 587186.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 116281 + 565504 = 341^2 + 752^2 .

It is a cyclic number.

It is not a de Polignac number, because 681785 - 2² = 681781 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 797 + ... + 1413.

It is an arithmetic number, because the mean of its divisors is an integer number (58401).

2⁶⁸¹⁷⁸⁵ is an apocalyptic number.

681785 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

681785 is a deficient number, since it is larger than the sum of its proper divisors (252631).

681785 is a wasteful number, since it uses less digits than its factorization.

681785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652.

The product of its digits is 13440, while the sum is 35.

The square root of 681785 is about 825.7027310116. The cubic root of 681785 is about 88.0134707340.

The spelling of 681785 in words is "six hundred eighty-one thousand, seven hundred eighty-five".