1644881648 has 60 divisors (see below), whose sum is σ = 3413329152. Its totient is φ = 767692800.

The previous prime is 1644881647. The next prime is 1644881717. The reversal of 1644881648 is 8461884461.

It is a junction number, because it is equal to n+sod(n) for n = 1644881596 and 1644881605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644881647) 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, 585848 + ... + 588648.

Almost surely, 2^1644881648 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 1644881648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1706664576).

1644881648 is an abundant number, since it is smaller than the sum of its proper divisors (1768447504).

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

1644881648 is a wasteful number, since it uses less digits than its factorization.

1644881648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2970 (or 2947 counting only the distinct ones).

The product of its digits is 1179648, while the sum is 50.

The square root of 1644881648 is about 40557.1405303678. The cubic root of 1644881648 is about 1180.4426300755.

The spelling of 1644881648 in words is "one billion, six hundred forty-four million, eight hundred eighty-one thousand, six hundred forty-eight".