644496 has 40 divisors (see below), whose sum is σ = 1726080. Its totient is φ = 206976.

The previous prime is 644491. The next prime is 644507. The reversal of 644496 is 694446.

It is not an unprimeable number, because it can be changed into a prime (644491) by changing a digit.

644496 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, 1161 + ... + 1623.

It is an arithmetic number, because the mean of its divisors is an integer number (43152).

2⁶⁴⁴⁴⁹⁶ 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 644496, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (863040).

644496 is an abundant number, since it is smaller than the sum of its proper divisors (1081584).

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

644496 is a wasteful number, since it uses less digits than its factorization.

644496 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503 (or 497 counting only the distinct ones).

The product of its digits is 20736, while the sum is 33.

The square root of 644496 is about 802.8050821962. The cubic root of 644496 is about 86.3787156076.

It can be divided in two parts, 64 and 4496, that added together give a triangular number (4560 = T₉₅).

The spelling of 644496 in words is "six hundred forty-four thousand, four hundred ninety-six".