646816 has 48 divisors (see below), whose sum is σ = 1428840. Its totient is φ = 286720.

The previous prime is 646781. The next prime is 646823. The reversal of 646816 is 618646.

646816 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 490000 + 156816 = 700^2 + 396^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15756 + ... + 15796.

2⁶⁴⁶⁸¹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (714420).

646816 is an abundant number, since it is smaller than the sum of its proper divisors (782024).

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

646816 is a wasteful number, since it uses less digits than its factorization.

646816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 89 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 646816 is about 804.2487177484. The cubic root of 646816 is about 86.4822376573.

The spelling of 646816 in words is "six hundred forty-six thousand, eight hundred sixteen".