644161013760 has 384 divisors, whose sum is σ = 2252256814080. Its totient is φ = 155875737600.

The previous prime is 644161013737. The next prime is 644161013801. The reversal of 644161013760 is 67310161446.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 230797965 + ... + 230800755.

It is an arithmetic number, because the mean of its divisors is an integer number (5865252120).

Almost surely, 2^644161013760 is an apocalyptic number.

644161013760 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 644161013760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1126128407040).

644161013760 is an abundant number, since it is smaller than the sum of its proper divisors (1608095800320).

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

644161013760 is a wasteful number, since it uses less digits than its factorization.

644161013760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3515 (or 3495 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 39.

The spelling of 644161013760 in words is "six hundred forty-four billion, one hundred sixty-one million, thirteen thousand, seven hundred sixty".