644868480 has 256 divisors, whose sum is σ = 2273702400. Its totient is φ = 154632192.

The previous prime is 644868439. The next prime is 644868481. The reversal of 644868480 is 84868446.

644868480 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644868481) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 750291 + ... + 751149.

It is an arithmetic number, because the mean of its divisors is an integer number (8881650).

Almost surely, 2^644868480 is an apocalyptic number.

644868480 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 644868480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1136851200).

644868480 is an abundant number, since it is smaller than the sum of its proper divisors (1628833920).

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

644868480 is a wasteful number, since it uses less digits than its factorization.

644868480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 921 (or 909 counting only the distinct ones).

The product of its (nonzero) digits is 1179648, while the sum is 48.

The square root of 644868480 is about 25394.2607689218. The cubic root of 644868480 is about 863.9535297366.

The spelling of 644868480 in words is "six hundred forty-four million, eight hundred sixty-eight thousand, four hundred eighty".