644096 has 44 divisors (see below), whose sum is σ = 1400148. Its totient is φ = 294912.

The previous prime is 644089. The next prime is 644101. The reversal of 644096 is 690446.

It can be written as a sum of positive squares in 2 ways, for example, as 541696 + 102400 = 736^2 + 320^2 .

It is a congruent number.

It is an unprimeable number.

644096 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 3 ways as a sum of consecutive naturals, for example, 17390 + ... + 17426.

2⁶⁴⁴⁰⁹⁶ 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 644096, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (700074).

644096 is an abundant number, since it is smaller than the sum of its proper divisors (756052).

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

644096 is a wasteful number, since it uses less digits than its factorization.

644096 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 56 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 644096 is about 802.5559170550. Note that the first 3 decimals coincide. The cubic root of 644096 is about 86.3608418805.

It can be divided in two parts, 64 and 4096, that multiplied together give a 18-th power (262144 = 2¹⁸).

The spelling of 644096 in words is "six hundred forty-four thousand, ninety-six".