644381248 has 84 divisors (see below), whose sum is σ = 1528226560. Its totient is φ = 264059136.

The previous prime is 644381239. The next prime is 644381249. The reversal of 644381248 is 842183446.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 644381248.

It is not an unprimeable number, because it can be changed into a prime (644381249) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 235633 + ... + 238351.

Almost surely, 2^644381248 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 644381248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (764113280).

644381248 is an abundant number, since it is smaller than the sum of its proper divisors (883845312).

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

644381248 is a wasteful number, since it uses less digits than its factorization.

644381248 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2784 (or 2751 counting only the distinct ones).

The product of its digits is 147456, while the sum is 40.

The square root of 644381248 is about 25384.6656074095. The cubic root of 644381248 is about 863.7358874941.

The spelling of 644381248 in words is "six hundred forty-four million, three hundred eighty-one thousand, two hundred forty-eight".