686758 has 4 divisors (see below), whose sum is σ = 1030140. Its totient is φ = 343378.

The previous prime is 686737. The next prime is 686761. The reversal of 686758 is 857686.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 857686 = 2 ⋅428843.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 686758.

It is a congruent number.

It is an unprimeable number.

686758 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 as a sum of consecutive naturals, namely, 171688 + ... + 171691.

It is an arithmetic number, because the mean of its divisors is an integer number (257535).

2⁶⁸⁶⁷⁵⁸ is an apocalyptic number.

686758 is a deficient number, since it is larger than the sum of its proper divisors (343382).

686758 is a wasteful number, since it uses less digits than its factorization.

686758 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343381.

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

The square root of 686758 is about 828.7086339601. The cubic root of 686758 is about 88.2269452144.

It can be divided in two parts, 686 and 758, that added together give a square (1444 = 38²).

The spelling of 686758 in words is "six hundred eighty-six thousand, seven hundred fifty-eight".