644028224 has 112 divisors (see below), whose sum is σ = 1529364480. Its totient is φ = 263278080.

The previous prime is 644028191. The next prime is 644028241. The reversal of 644028224 is 422820446.

It is a tau number, because it is divible by the number of its divisors (112).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1096859 + ... + 1097445.

It is an arithmetic number, because the mean of its divisors is an integer number (13655040).

Almost surely, 2^644028224 is an apocalyptic number.

644028224 is a gapful number since it is divisible by the number (64) 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 644028224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (764682240).

644028224 is an abundant number, since it is smaller than the sum of its proper divisors (885336256).

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

644028224 is a wasteful number, since it uses less digits than its factorization.

644028224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716 (or 706 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 32.

The square root of 644028224 is about 25377.7111655090. The cubic root of 644028224 is about 863.5781262313.

The spelling of 644028224 in words is "six hundred forty-four million, twenty-eight thousand, two hundred twenty-four".