644112040 has 192 divisors, whose sum is σ = 1779699600. Its totient is φ = 208158720.

The previous prime is 644112037. The next prime is 644112041. The reversal of 644112040 is 40211446.

644112040 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 139570596 + 504541444 = 11814^2 + 22462^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644112041) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1824504 + ... + 1824856.

Almost surely, 2^644112040 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 644112040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (889849800).

644112040 is an abundant number, since it is smaller than the sum of its proper divisors (1135587560).

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

644112040 is a wasteful number, since it uses less digits than its factorization.

644112040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428 (or 413 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 644112040 is about 25379.3624821428. The cubic root of 644112040 is about 863.6155875939.

Adding to 644112040 its reverse (40211446), we get a palindrome (684323486).

It can be divided in two parts, 6441 and 12040, that added together give a palindrome (18481).

The spelling of 644112040 in words is "six hundred forty-four million, one hundred twelve thousand, forty".