685780 has 24 divisors (see below), whose sum is σ = 1525608. Its totient is φ = 258048.

The previous prime is 685759. The next prime is 685781. The reversal of 685780 is 87586.

It can be written as a sum of positive squares in 4 ways, for example, as 258064 + 427716 = 508^2 + 654^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685781) 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 7 ways as a sum of consecutive naturals, for example, 669 + ... + 1348.

It is an arithmetic number, because the mean of its divisors is an integer number (63567).

2⁶⁸⁵⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

685780 is an abundant number, since it is smaller than the sum of its proper divisors (839828).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

685780 is a wasteful number, since it uses less digits than its factorization.

685780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2043 (or 2041 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 685780 is about 828.1183490299. The cubic root of 685780 is about 88.1850445040.

The spelling of 685780 in words is "six hundred eighty-five thousand, seven hundred eighty".