644424480 has 216 divisors, whose sum is σ = 2558415132. Its totient is φ = 147280896.

The previous prime is 644424479. The next prime is 644424503. The reversal of 644424480 is 84424446.

644424480 is a `hidden beast` number, since 644 + 4 + 2 + 4 + 4 + 8 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 639280656 + 5143824 = 25284^2 + 2268^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 65994 + ... + 75126.

Almost surely, 2^644424480 is an apocalyptic number.

644424480 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 644424480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1279207566).

644424480 is an abundant number, since it is smaller than the sum of its proper divisors (1913990652).

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

644424480 is a wasteful number, since it uses less digits than its factorization.

644424480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9168 (or 9150 counting only the distinct ones).

The product of its (nonzero) digits is 98304, while the sum is 36.

The square root of 644424480 is about 25385.5171308366. The cubic root of 644424480 is about 863.7552032822.

The spelling of 644424480 in words is "six hundred forty-four million, four hundred twenty-four thousand, four hundred eighty".