644539109760 has 3584 divisors, whose sum is σ = 3236483174400. Its totient is φ = 118674948096.

The previous prime is 644539109759. The next prime is 644539109791. The reversal of 644539109760 is 67901935446.

644539109760 is a `hidden beast` number, since 6 + 4 + 4 + 539 + 10 + 97 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 644539109697 and 644539109706.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 447 ways as a sum of consecutive naturals, for example, 13713598057 + ... + 13713598103.

It is an arithmetic number, because the mean of its divisors is an integer number (903036600).

Almost surely, 2^644539109760 is an apocalyptic number.

644539109760 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 644539109760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1618241587200).

644539109760 is an abundant number, since it is smaller than the sum of its proper divisors (2591944064640).

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

644539109760 is a wasteful number, since it uses less digits than its factorization.

644539109760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 113 counting only the distinct ones).

The product of its (nonzero) digits is 4898880, while the sum is 54.

The spelling of 644539109760 in words is "six hundred forty-four billion, five hundred thirty-nine million, one hundred nine thousand, seven hundred sixty".