644608474560 has 672 divisors, whose sum is σ = 2329003622400. Its totient is φ = 163452764160.

The previous prime is 644608474513. The next prime is 644608474613. The reversal of 644608474560 is 65474806446.

It is a happy number.

644608474560 is a `hidden beast` number, since 6 + 4 + 4 + 6 + 0 + 8 + 4 + 74 + 560 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 644608474497 and 644608474506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1576059636 + ... + 1576060044.

It is an arithmetic number, because the mean of its divisors is an integer number (3465779200).

Almost surely, 2^644608474560 is an apocalyptic number.

644608474560 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 644608474560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1164501811200).

644608474560 is an abundant number, since it is smaller than the sum of its proper divisors (1684395147840).

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

644608474560 is a wasteful number, since it uses less digits than its factorization.

644608474560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729 (or 716 counting only the distinct ones).

The product of its (nonzero) digits is 15482880, while the sum is 54.

The spelling of 644608474560 in words is "six hundred forty-four billion, six hundred eight million, four hundred seventy-four thousand, five hundred sixty".