644046 has 32 divisors (see below), whose sum is σ = 1451520. Its totient is φ = 189024.

The previous prime is 644029. The next prime is 644047. The reversal of 644046 is 640446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1615 + ... + 1973.

It is an arithmetic number, because the mean of its divisors is an integer number (45360).

2⁶⁴⁴⁰⁴⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644046, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (725760).

644046 is an abundant number, since it is smaller than the sum of its proper divisors (807474).

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

644046 is a wasteful number, since it uses less digits than its factorization.

644046 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400.

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 644046 is about 802.5247659730. The cubic root of 644046 is about 86.3586071444.

Subtracting from 644046 its reverse (640446), we obtain a square (3600 = 60²).

The spelling of 644046 in words is "six hundred forty-four thousand, forty-six".