644336 has 40 divisors (see below), whose sum is σ = 1559424. Its totient is φ = 250560.

The previous prime is 644327. The next prime is 644341. The reversal of 644336 is 633446.

644336 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 unprimeable number.

644336 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 7 ways as a sum of consecutive naturals, for example, 971 + ... + 1493.

2⁶⁴⁴³³⁶ 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 644336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (779712).

644336 is an abundant number, since it is smaller than the sum of its proper divisors (915088).

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

644336 is a wasteful number, since it uses less digits than its factorization.

644336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549 (or 543 counting only the distinct ones).

The product of its digits is 5184, while the sum is 26.

The square root of 644336 is about 802.7054254208. The cubic root of 644336 is about 86.3715670044.

The spelling of 644336 in words is "six hundred forty-four thousand, three hundred thirty-six".