1643684443 has 8 divisors (see below), whose sum is σ = 1719138816. Its totient is φ = 1568562600.

The previous prime is 1643684431. The next prime is 1643684453. The reversal of 1643684443 is 3444863461.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643684443 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1643684443.

It is not an unprimeable number, because it can be changed into a prime (1643684453) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72993 + ... + 92818.

It is an arithmetic number, because the mean of its divisors is an integer number (214892352).

Almost surely, 2^1643684443 is an apocalyptic number.

1643684443 is a deficient number, since it is larger than the sum of its proper divisors (75454373).

1643684443 is a wasteful number, since it uses less digits than its factorization.

1643684443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166265.

The product of its digits is 663552, while the sum is 43.

The square root of 1643684443 is about 40542.3783589468. The cubic root of 1643684443 is about 1180.1561707981.

The spelling of 1643684443 in words is "one billion, six hundred forty-three million, six hundred eighty-four thousand, four hundred forty-three".