644072 has 32 divisors (see below), whose sum is σ = 1421280. Its totient is φ = 269760.

The previous prime is 644057. The next prime is 644089. The reversal of 644072 is 270446.

It is a congruent number.

It is an unprimeable number.

644072 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 7 ways as a sum of consecutive naturals, for example, 863 + ... + 1425.

It is an arithmetic number, because the mean of its divisors is an integer number (44415).

2⁶⁴⁴⁰⁷² 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 644072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (710640).

644072 is an abundant number, since it is smaller than the sum of its proper divisors (777208).

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

644072 is a wasteful number, since it uses less digits than its factorization.

644072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593 (or 589 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 644072 is about 802.5409646865. The cubic root of 644072 is about 86.3597692216.

The spelling of 644072 in words is "six hundred forty-four thousand, seventy-two".