644978484 has 144 divisors (see below), whose sum is σ = 1797344640. Its totient is φ = 199946880.

The previous prime is 644978483. The next prime is 644978497. The reversal of 644978484 is 484879446.

644978484 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 644978484.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644978483) 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, 2768032 + ... + 2768264.

It is an arithmetic number, because the mean of its divisors is an integer number (12481560).

Almost surely, 2^644978484 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 644978484, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (898672320).

644978484 is an abundant number, since it is smaller than the sum of its proper divisors (1152366156).

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

644978484 is a wasteful number, since it uses less digits than its factorization.

644978484 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355 (or 328 counting only the distinct ones).

The product of its digits is 6193152, while the sum is 54.

The square root of 644978484 is about 25396.4265990316. The cubic root of 644978484 is about 864.0026523838.

The spelling of 644978484 in words is "six hundred forty-four million, nine hundred seventy-eight thousand, four hundred eighty-four".