644920224 has 144 divisors (see below), whose sum is σ = 1853494272. Its totient is φ = 196245504.

The previous prime is 644920223. The next prime is 644920261. The reversal of 644920224 is 422029446.

It is not an unprimeable number, because it can be changed into a prime (644920223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2060292 + ... + 2060604.

It is an arithmetic number, because the mean of its divisors is an integer number (12871488).

Almost surely, 2^644920224 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 644920224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (926747136).

644920224 is an abundant number, since it is smaller than the sum of its proper divisors (1208574048).

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

644920224 is a wasteful number, since it uses less digits than its factorization.

644920224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 479 (or 458 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 33.

The square root of 644920224 is about 25395.2795613673. The cubic root of 644920224 is about 863.9766368854.

The spelling of 644920224 in words is "six hundred forty-four million, nine hundred twenty thousand, two hundred twenty-four".