644304240 has 160 divisors (see below), whose sum is σ = 2228696640. Its totient is φ = 171085824.

The previous prime is 644304229. The next prime is 644304253. The reversal of 644304240 is 42403446.

644304240 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 (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 675604 + ... + 676556.

It is an arithmetic number, because the mean of its divisors is an integer number (13929354).

Almost surely, 2^644304240 is an apocalyptic number.

644304240 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 644304240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114348320).

644304240 is an abundant number, since it is smaller than the sum of its proper divisors (1584392400).

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

644304240 is a wasteful number, since it uses less digits than its factorization.

644304240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288 (or 1276 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 27.

The square root of 644304240 is about 25383.1487408477. The cubic root of 644304240 is about 863.7014786597.

Adding to 644304240 its reverse (42403446), we get a palindrome (686707686).

The spelling of 644304240 in words is "six hundred forty-four million, three hundred four thousand, two hundred forty".