644358 has 32 divisors (see below), whose sum is σ = 1516032. Its totient is φ = 180000.

The previous prime is 644353. The next prime is 644359. The reversal of 644358 is 853446.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644358.

It is not an unprimeable number, because it can be changed into a prime (644353) by changing a digit.

644358 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 15 ways as a sum of consecutive naturals, for example, 483 + ... + 1233.

It is an arithmetic number, because the mean of its divisors is an integer number (47376).

2⁶⁴⁴³⁵⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644358, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (758016).

644358 is an abundant number, since it is smaller than the sum of its proper divisors (871674).

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

644358 is a wasteful number, since it uses less digits than its factorization.

644358 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780.

The product of its digits is 11520, while the sum is 30.

The square root of 644358 is about 802.7191289611. The cubic root of 644358 is about 86.3725500075.

The spelling of 644358 in words is "six hundred forty-four thousand, three hundred fifty-eight".