1644636648 has 16 divisors (see below), whose sum is σ = 4111591680. Its totient is φ = 548212208.

The previous prime is 1644636629. The next prime is 1644636659. The reversal of 1644636648 is 8466364461.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 1644636597 and 1644636606.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34263240 + ... + 34263287.

It is an arithmetic number, because the mean of its divisors is an integer number (256974480).

Almost surely, 2^1644636648 is an apocalyptic number.

It is an amenable number.

1644636648 is an abundant number, since it is smaller than the sum of its proper divisors (2466955032).

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

1644636648 is a wasteful number, since it uses less digits than its factorization.

1644636648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68526536 (or 68526532 counting only the distinct ones).

The product of its digits is 1990656, while the sum is 48.

The square root of 1644636648 is about 40554.1199879864. The cubic root of 1644636648 is about 1180.3840194140.

The spelling of 1644636648 in words is "one billion, six hundred forty-four million, six hundred thirty-six thousand, six hundred forty-eight".