646784 has 32 divisors (see below), whose sum is σ = 1338240. Its totient is φ = 311040.

The previous prime is 646781. The next prime is 646823. The reversal of 646784 is 487646.

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (646781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3887 + ... + 4049.

It is an arithmetic number, because the mean of its divisors is an integer number (41820).

2⁶⁴⁶⁷⁸⁴ is an apocalyptic number.

646784 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (669120).

646784 is an abundant number, since it is smaller than the sum of its proper divisors (691456).

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

646784 is a wasteful number, since it uses less digits than its factorization.

646784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208 (or 196 counting only the distinct ones).

The product of its digits is 32256, while the sum is 35.

The square root of 646784 is about 804.2288231592. The cubic root of 646784 is about 86.4808114520.

The spelling of 646784 in words is "six hundred forty-six thousand, seven hundred eighty-four".