1643138784 has 144 divisors (see below), whose sum is σ = 5538169728. Its totient is φ = 469452672.

The previous prime is 1643138779. The next prime is 1643138839. The reversal of 1643138784 is 4878313461.

1643138784 is a `hidden beast` number, since 164 + 31 + 387 + 84 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 39339 + ... + 69525.

It is an arithmetic number, because the mean of its divisors is an integer number (38459512).

Almost surely, 2^1643138784 is an apocalyptic number.

1643138784 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643138784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2769084864).

1643138784 is an abundant number, since it is smaller than the sum of its proper divisors (3895030944).

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

1643138784 is an equidigital number, since it uses as much as digits as its factorization.

1643138784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30219 (or 30199 counting only the distinct ones).

The product of its digits is 387072, while the sum is 45.

The square root of 1643138784 is about 40535.6483110854. The cubic root of 1643138784 is about 1180.0255629816.

The spelling of 1643138784 in words is "one billion, six hundred forty-three million, one hundred thirty-eight thousand, seven hundred eighty-four".