644311220 has 48 divisors (see below), whose sum is σ = 1637314560. Its totient is φ = 207911424.

The previous prime is 644311207. The next prime is 644311231. The reversal of 644311220 is 22113446.

644311220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 132980 + ... + 137739.

It is an arithmetic number, because the mean of its divisors is an integer number (34110720).

Almost surely, 2^644311220 is an apocalyptic number.

It is an amenable number.

644311220 is an abundant number, since it is smaller than the sum of its proper divisors (993003340).

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

644311220 is a wasteful number, since it uses less digits than its factorization.

644311220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270752 (or 270750 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 644311220 is about 25383.2862332677. The cubic root of 644311220 is about 863.7045975871.

Adding to 644311220 its reverse (22113446), we get a palindrome (666424666).

The spelling of 644311220 in words is "six hundred forty-four million, three hundred eleven thousand, two hundred twenty".