644913360 has 640 divisors, whose sum is σ = 2909813760. Its totient is φ = 127401984.

The previous prime is 644913341. The next prime is 644913361. The reversal of 644913360 is 63319446.

644913360 = 127² + 128² + ... + 1246².

644913360 is a `hidden beast` number, since 644 + 9 + 1 + 3 + 3 + 6 + 0 = 666.

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

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644913361) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3341424 + ... + 3341616.

It is an arithmetic number, because the mean of its divisors is an integer number (4546584).

Almost surely, 2^644913360 is an apocalyptic number.

644913360 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 644913360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1454906880).

644913360 is an abundant number, since it is smaller than the sum of its proper divisors (2264900400).

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

644913360 is a wasteful number, since it uses less digits than its factorization.

644913360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 240 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 36.

The square root of 644913360 is about 25395.1444177819. The cubic root of 644913360 is about 863.9735717225.

The spelling of 644913360 in words is "six hundred forty-four million, nine hundred thirteen thousand, three hundred sixty".