644850013824 has 384 divisors, whose sum is σ = 1942759728000. Its totient is φ = 205111222272.

The previous prime is 644850013823. The next prime is 644850013849. The reversal of 644850013824 is 428310058446.

644850013824 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 500 + 138 + 2 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×644850013824² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644850013824.

It is not an unprimeable number, because it can be changed into a prime (644850013823) 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, 996676669 + ... + 996677315.

It is an arithmetic number, because the mean of its divisors is an integer number (5059270125).

Almost surely, 2^644850013824 is an apocalyptic number.

644850013824 is a gapful number since it is divisible by the number (64) 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 644850013824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (971379864000).

644850013824 is an abundant number, since it is smaller than the sum of its proper divisors (1297909714176).

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

644850013824 is a wasteful number, since it uses less digits than its factorization.

644850013824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1120 (or 1105 counting only the distinct ones).

The product of its (nonzero) digits is 737280, while the sum is 45.

The spelling of 644850013824 in words is "six hundred forty-four billion, eight hundred fifty million, thirteen thousand, eight hundred twenty-four".