644334876 has 144 divisors (see below), whose sum is σ = 1783541760. Its totient is φ = 195592320.

The previous prime is 644334863. The next prime is 644334877. The reversal of 644334876 is 678433446.

644334876 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

Its product of digits (1161216) is a multiple of the sum of its prime factors (576).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644334877) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1391421 + ... + 1391883.

Almost surely, 2^644334876 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 644334876, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (891770880).

644334876 is an abundant number, since it is smaller than the sum of its proper divisors (1139206884).

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

644334876 is a wasteful number, since it uses less digits than its factorization.

644334876 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576 (or 571 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 45.

The square root of 644334876 is about 25383.7522049046. The cubic root of 644334876 is about 863.7151678133.

The spelling of 644334876 in words is "six hundred forty-four million, three hundred thirty-four thousand, eight hundred seventy-six".