644561076 has 48 divisors (see below), whose sum is σ = 1582257600. Its totient is φ = 203922432.

The previous prime is 644561059. The next prime is 644561077. The reversal of 644561076 is 670165446.

644561076 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644561077) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4836 + ... + 36228.

It is an arithmetic number, because the mean of its divisors is an integer number (32963700).

Almost surely, 2^644561076 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 644561076, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (791128800).

644561076 is an abundant number, since it is smaller than the sum of its proper divisors (937696524).

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

644561076 is a wasteful number, since it uses less digits than its factorization.

644561076 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31488 (or 31486 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 39.

The square root of 644561076 is about 25388.2074199814. The cubic root of 644561076 is about 863.8162278470.

The spelling of 644561076 in words is "six hundred forty-four million, five hundred sixty-one thousand, seventy-six".