644088 has 32 divisors (see below), whose sum is σ = 1647360. Its totient is φ = 209760.

The previous prime is 644057. The next prime is 644089. The reversal of 644088 is 880446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644089) by changing a digit.

644088 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, 843 + ... + 1413.

It is an arithmetic number, because the mean of its divisors is an integer number (51480).

2⁶⁴⁴⁰⁸⁸ 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 644088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (823680).

644088 is an abundant number, since it is smaller than the sum of its proper divisors (1003272).

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

644088 is a wasteful number, since it uses less digits than its factorization.

644088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627 (or 623 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 30.

The square root of 644088 is about 802.5509329631. The cubic root of 644088 is about 86.3604843305.

The spelling of 644088 in words is "six hundred forty-four thousand, eighty-eight".