686406 has 32 divisors (see below), whose sum is σ = 1601280. Its totient is φ = 192096.

The previous prime is 686363. The next prime is 686417. The reversal of 686406 is 604686.

It is a happy number.

686406 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 686406.

It is an unprimeable number.

686406 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 in 15 ways as a sum of consecutive naturals, for example, 2340 + ... + 2616.

It is an arithmetic number, because the mean of its divisors is an integer number (50040).

2⁶⁸⁶⁴⁰⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686406, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (800640).

686406 is an abundant number, since it is smaller than the sum of its proper divisors (914874).

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

686406 is a wasteful number, since it uses less digits than its factorization.

686406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 686406 is about 828.4962281145. The cubic root of 686406 is about 88.2118689711.

The spelling of 686406 in words is "six hundred eighty-six thousand, four hundred six".