686618 has 4 divisors (see below), whose sum is σ = 1029930. Its totient is φ = 343308.

The previous prime is 686611. The next prime is 686639. The reversal of 686618 is 816686.

686618 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in only one way, i.e., 573049 + 113569 = 757^2 + 337^2 .

It is not an unprimeable number, because it can be changed into a prime (686611) by changing a digit.

686618 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 171653 + ... + 171656.

2⁶⁸⁶⁶¹⁸ is an apocalyptic number.

686618 is a deficient number, since it is larger than the sum of its proper divisors (343312).

686618 is a wasteful number, since it uses less digits than its factorization.

686618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343311.

The product of its digits is 13824, while the sum is 35.

The square root of 686618 is about 828.6241608836. The cubic root of 686618 is about 88.2209495984.

The spelling of 686618 in words is "six hundred eighty-six thousand, six hundred eighteen".