646686 has 24 divisors (see below), whose sum is σ = 1440504. Its totient is φ = 209520.

The previous prime is 646669. The next prime is 646687. The reversal of 646686 is 686646.

646686 is a `hidden beast` number, since 646 + 6 + 8 + 6 = 666.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 646686.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646687) by changing a digit.

646686 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 11 ways as a sum of consecutive naturals, for example, 181 + ... + 1151.

It is an arithmetic number, because the mean of its divisors is an integer number (60021).

2⁶⁴⁶⁶⁸⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (720252).

646686 is an abundant number, since it is smaller than the sum of its proper divisors (793818).

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

646686 is a wasteful number, since it uses less digits than its factorization.

646686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1016 (or 1013 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 646686 is about 804.1678929179. The cubic root of 646686 is about 86.4764434055.

The spelling of 646686 in words is "six hundred forty-six thousand, six hundred eighty-six".