1643626944 has 224 divisors, whose sum is σ = 5079674880. Its totient is φ = 520473600.

The previous prime is 1643626909. The next prime is 1643626961. The reversal of 1643626944 is 4496263461.

1643626944 is a `hidden beast` number, since 16 + 4 + 3 + 626 + 9 + 4 + 4 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 1643626944.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3267397 + ... + 3267899.

It is an arithmetic number, because the mean of its divisors is an integer number (22677120).

Almost surely, 2^1643626944 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 1643626944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2539837440).

1643626944 is an abundant number, since it is smaller than the sum of its proper divisors (3436047936).

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

1643626944 is a wasteful number, since it uses less digits than its factorization.

1643626944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 616 (or 600 counting only the distinct ones).

The product of its digits is 746496, while the sum is 45.

The square root of 1643626944 is about 40541.6692305583. The cubic root of 1643626944 is about 1180.1424093183.

The spelling of 1643626944 in words is "one billion, six hundred forty-three million, six hundred twenty-six thousand, nine hundred forty-four".