678785 has 4 divisors (see below), whose sum is σ = 814548. Its totient is φ = 543024.

The previous prime is 678779. The next prime is 678809. The reversal of 678785 is 587876.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 126736 + 552049 = 356^2 + 743^2 .

It is a cyclic number.

It is not a de Polignac number, because 678785 - 2⁶ = 678721 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67874 + ... + 67883.

It is an arithmetic number, because the mean of its divisors is an integer number (203637).

2⁶⁷⁸⁷⁸⁵ is an apocalyptic number.

It is an amenable number.

678785 is a deficient number, since it is larger than the sum of its proper divisors (135763).

678785 is a wasteful number, since it uses less digits than its factorization.

678785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135762.

The product of its digits is 94080, while the sum is 41.

The square root of 678785 is about 823.8840937899. The cubic root of 678785 is about 87.8841882183.

Subtracting from 678785 its reverse (587876), we obtain a palindrome (90909).

The spelling of 678785 in words is "six hundred seventy-eight thousand, seven hundred eighty-five".