644560 has 40 divisors (see below), whose sum is σ = 1714176. Its totient is φ = 220800.

The previous prime is 644557. The next prime is 644563. The reversal of 644560 is 65446.

It is a happy number.

644560 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (644557) and next prime (644563).

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16 + ... + 1135.

2⁶⁴⁴⁵⁶⁰ 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 644560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (857088).

644560 is an abundant number, since it is smaller than the sum of its proper divisors (1069616).

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

644560 is a wasteful number, since it uses less digits than its factorization.

644560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1171 (or 1165 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 644560 is about 802.8449414426. The cubic root of 644560 is about 86.3815747175.

It can be divided in two parts, 64 and 4560, that added together give a square (4624 = 68²).

The spelling of 644560 in words is "six hundred forty-four thousand, five hundred sixty".