644048064 has 224 divisors, whose sum is σ = 2134087680. Its totient is φ = 188697600.

The previous prime is 644048063. The next prime is 644048101. The reversal of 644048064 is 460840446.

644048064 is a `hidden beast` number, since 644 + 0 + 4 + 8 + 0 + 6 + 4 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644048063) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 588702 + ... + 589794.

Almost surely, 2^644048064 is an apocalyptic number.

644048064 is a gapful number since it is divisible by the number (64) 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 644048064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1067043840).

644048064 is an abundant number, since it is smaller than the sum of its proper divisors (1490039616).

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

644048064 is a wasteful number, since it uses less digits than its factorization.

644048064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156 (or 1140 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 36.

The square root of 644048064 is about 25378.1020566945. The cubic root of 644048064 is about 863.5869939659.

The spelling of 644048064 in words is "six hundred forty-four million, forty-eight thousand, sixty-four".