678685 has 8 divisors (see below), whose sum is σ = 930816. Its totient is φ = 465360.

The previous prime is 678659. The next prime is 678719. The reversal of 678685 is 586876.

678685 = 256² + 257² + ... + 265².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 678685 - 2⁵ = 678653 is a prime.

It is a super-2 number, since 2×678685² = 921226658450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 9661 + ... + 9730.

It is an arithmetic number, because the mean of its divisors is an integer number (116352).

2⁶⁷⁸⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

678685 is a deficient number, since it is larger than the sum of its proper divisors (252131).

678685 is a wasteful number, since it uses less digits than its factorization.

678685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19403.

The product of its digits is 80640, while the sum is 40.

The square root of 678685 is about 823.8234034063. The cubic root of 678685 is about 87.8798722467.

Subtracting from 678685 its reverse (586876), we obtain a square (91809 = 303²).

The spelling of 678685 in words is "six hundred seventy-eight thousand, six hundred eighty-five".