644408160 has 288 divisors, whose sum is σ = 2306174976. Its totient is φ = 149990400.

The previous prime is 644408153. The next prime is 644408189. The reversal of 644408160 is 61804446.

It is a Harshad number since it is a multiple of its sum of digits (33).

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 47 ways as a sum of consecutive naturals, for example, 5074017 + ... + 5074143.

It is an arithmetic number, because the mean of its divisors is an integer number (8007552).

Almost surely, 2^644408160 is an apocalyptic number.

644408160 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 644408160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1153087488).

644408160 is an abundant number, since it is smaller than the sum of its proper divisors (1661766816).

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

644408160 is a wasteful number, since it uses less digits than its factorization.

644408160 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 33.

The square root of 644408160 is about 25385.1956856748. The cubic root of 644408160 is about 863.7479117094.

It can be divided in two parts, 644 and 408160, that added together give a palindrome (408804).

The spelling of 644408160 in words is "six hundred forty-four million, four hundred eight thousand, one hundred sixty".