644112722400 has 1728 divisors, whose sum is σ = 2693077632000. Its totient is φ = 132843110400.

The previous prime is 644112722389. The next prime is 644112722417. The reversal of 644112722400 is 4227211446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 7237221556 + ... + 7237221644.

It is an arithmetic number, because the mean of its divisors is an integer number (1558494000).

Almost surely, 2^644112722400 is an apocalyptic number.

644112722400 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 644112722400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1346538816000).

644112722400 is an abundant number, since it is smaller than the sum of its proper divisors (2048964909600).

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

644112722400 is a wasteful number, since it uses less digits than its factorization.

644112722400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 33.

Adding to 644112722400 its reverse (4227211446), we get a palindrome (648339933846).

The spelling of 644112722400 in words is "six hundred forty-four billion, one hundred twelve million, seven hundred twenty-two thousand, four hundred".