644322000 has 480 divisors, whose sum is σ = 2567335680. Its totient is φ = 136012800.

The previous prime is 644321989. The next prime is 644322037. The reversal of 644322000 is 223446.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a nialpdrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 22217986 + ... + 22218014.

It is an arithmetic number, because the mean of its divisors is an integer number (5348616).

Almost surely, 2^644322000 is an apocalyptic number.

644322000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644322000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1283667840).

644322000 is an abundant number, since it is smaller than the sum of its proper divisors (1923013680).

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

644322000 is a wasteful number, since it uses less digits than its factorization.

644322000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 644322000 is about 25383.4985768314. The cubic root of 644322000 is about 863.7094144537.

Adding to 644322000 its reverse (223446), we get a palindrome (644545446).

The spelling of 644322000 in words is "six hundred forty-four million, three hundred twenty-two thousand".