644700056 has 256 divisors, whose sum is σ = 1741824000. Its totient is φ = 220147200.

The previous prime is 644700047. The next prime is 644700059. The reversal of 644700056 is 650007446.

It is a junction number, because it is equal to n+sod(n) for n = 644699995 and 644700031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644700059) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12164126 + ... + 12164178.

It is an arithmetic number, because the mean of its divisors is an integer number (6804000).

Almost surely, 2^644700056 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 644700056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (870912000).

644700056 is an abundant number, since it is smaller than the sum of its proper divisors (1097123944).

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

644700056 is a wasteful number, since it uses less digits than its factorization.

644700056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 32.

The square root of 644700056 is about 25390.9443699914. The cubic root of 644700056 is about 863.8783086212.

The spelling of 644700056 in words is "six hundred forty-four million, seven hundred thousand, fifty-six".