1644265656 has 160 divisors (see below), whose sum is σ = 5045554800. Its totient is φ = 496143360.

The previous prime is 1644265633. The next prime is 1644265657. The reversal of 1644265656 is 6565624461.

1644265656 is a `hidden beast` number, since 1 + 64 + 4 + 26 + 565 + 6 = 666.

It is a super-3 number, since 3×1644265656³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644265657) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2772496 + ... + 2773088.

Almost surely, 2^1644265656 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 1644265656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2522777400).

1644265656 is an abundant number, since it is smaller than the sum of its proper divisors (3401289144).

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

1644265656 is a wasteful number, since it uses less digits than its factorization.

1644265656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1011 (or 998 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 45.

The square root of 1644265656 is about 40549.5456941258. The cubic root of 1644265656 is about 1180.2952569589.

The spelling of 1644265656 in words is "one billion, six hundred forty-four million, two hundred sixty-five thousand, six hundred fifty-six".