644984734240 has 288 divisors, whose sum is σ = 2035476475200. Its totient is φ = 190452971520.

The previous prime is 644984734217. The next prime is 644984734241. The reversal of 644984734240 is 42437489446.

It is a Harshad number since it is a multiple of its sum of digits (55).

It is not an unprimeable number, because it can be changed into a prime (644984734241) 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, 1441746 + ... + 1835374.

It is an arithmetic number, because the mean of its divisors is an integer number (7067626650).

Almost surely, 2^644984734240 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 644984734240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1017738237600).

644984734240 is an abundant number, since it is smaller than the sum of its proper divisors (1390491740960).

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

644984734240 is a wasteful number, since it uses less digits than its factorization.

644984734240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393688 (or 393673 counting only the distinct ones).

The product of its (nonzero) digits is 18579456, while the sum is 55.

The spelling of 644984734240 in words is "six hundred forty-four billion, nine hundred eighty-four million, seven hundred thirty-four thousand, two hundred forty".