644426496 has 288 divisors, whose sum is σ = 2295820800. Its totient is φ = 174182400.

The previous prime is 644426473. The next prime is 644426501. The reversal of 644426496 is 694624446.

644426496 is a `hidden beast` number, since 64 + 442 + 64 + 96 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 918946 + ... + 919646.

It is an arithmetic number, because the mean of its divisors is an integer number (7971600).

Almost surely, 2^644426496 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644426496, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1147910400).

644426496 is an abundant number, since it is smaller than the sum of its proper divisors (1651394304).

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

644426496 is a wasteful number, since it uses less digits than its factorization.

644426496 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 752 (or 732 counting only the distinct ones).

The product of its digits is 995328, while the sum is 45.

The square root of 644426496 is about 25385.5568384859. The cubic root of 644426496 is about 863.7561039973.

The spelling of 644426496 in words is "six hundred forty-four million, four hundred twenty-six thousand, four hundred ninety-six".