644426029968 has 480 divisors, whose sum is σ = 2095280893440. Its totient is φ = 169601402880.

The previous prime is 644426029957. The next prime is 644426029991. The reversal of 644426029968 is 869920624446.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1002217455 + ... + 1002218097.

It is an arithmetic number, because the mean of its divisors is an integer number (4365168528).

Almost surely, 2^644426029968 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 644426029968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1047640446720).

644426029968 is an abundant number, since it is smaller than the sum of its proper divisors (1450854863472).

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

644426029968 is a wasteful number, since it uses less digits than its factorization.

644426029968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1275 (or 1262 counting only the distinct ones).

The product of its (nonzero) digits is 35831808, while the sum is 60.

The spelling of 644426029968 in words is "six hundred forty-four billion, four hundred twenty-six million, twenty-nine thousand, nine hundred sixty-eight".