644112500 has 54 divisors (see below), whose sum is σ = 1415139894. Its totient is φ = 256510000.

The previous prime is 644112479. The next prime is 644112503. The reversal of 644112500 is 5211446.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 3 ways, for example, as 297631504 + 346480996 = 17252^2 + 18614^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644112503) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2837387 + ... + 2837613.

Almost surely, 2^644112500 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 644112500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (707569947).

644112500 is an abundant number, since it is smaller than the sum of its proper divisors (771027394).

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

644112500 is an frugal number, since it uses more digits than its factorization.

644112500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 483 (or 234 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 644112500 is about 25379.3715446226. The cubic root of 644112500 is about 863.6157931808.

Adding to 644112500 its reverse (5211446), we get a palindrome (649323946).

The spelling of 644112500 in words is "six hundred forty-four million, one hundred twelve thousand, five hundred".