646624 has 36 divisors (see below), whose sum is σ = 1407672. Its totient is φ = 292160.

The previous prime is 646619. The next prime is 646631. The reversal of 646624 is 426646.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 646592 and 646601.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3789 + ... + 3955.

It is an arithmetic number, because the mean of its divisors is an integer number (39102).

2⁶⁴⁶⁶²⁴ 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 646624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (703836).

646624 is an abundant number, since it is smaller than the sum of its proper divisors (761048).

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

646624 is a wasteful number, since it uses less digits than its factorization.

646624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 180 counting only the distinct ones).

The product of its digits is 6912, while the sum is 28.

The square root of 646624 is about 804.1293428299. The cubic root of 646624 is about 86.4736797197.

The spelling of 646624 in words is "six hundred forty-six thousand, six hundred twenty-four".