644822156160 has 2304 divisors, whose sum is σ = 3029181442560. Its totient is φ = 129675313152.

The previous prime is 644822156057. The next prime is 644822156177. The reversal of 644822156160 is 61651228446.

It is a happy number.

644822156160 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 2 + 21 + 5 + 616 + 0 = 666.

It is a super-2 number, since 2×644822156160² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 2278523379 + ... + 2278523661.

It is an arithmetic number, because the mean of its divisors is an integer number (1314748890).

Almost surely, 2^644822156160 is an apocalyptic number.

644822156160 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 644822156160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1514590721280).

644822156160 is an abundant number, since it is smaller than the sum of its proper divisors (2384359286400).

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

644822156160 is a wasteful number, since it uses less digits than its factorization.

644822156160 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367 (or 336 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The spelling of 644822156160 in words is "six hundred forty-four billion, eight hundred twenty-two million, one hundred fifty-six thousand, one hundred sixty".