644960 has 48 divisors (see below), whose sum is σ = 1587600. Its totient is φ = 247296.

The previous prime is 644951. The next prime is 644977. The reversal of 644960 is 69446.

644960 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

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, 4571 + ... + 4709.

It is an arithmetic number, because the mean of its divisors is an integer number (33075).

2⁶⁴⁴⁹⁶⁰ is an apocalyptic number.

644960 is the 464-th octagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (793800).

644960 is an abundant number, since it is smaller than the sum of its proper divisors (942640).

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

644960 is a wasteful number, since it uses less digits than its factorization.

644960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183 (or 175 counting only the distinct ones).

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

The square root of 644960 is about 803.0940169121. The cubic root of 644960 is about 86.3994398683.

The spelling of 644960 in words is "six hundred forty-four thousand, nine hundred sixty".