1638720000 has 300 divisors, whose sum is σ = 5920315830. Its totient is φ = 436224000.

The previous prime is 1638719983. The next prime is 1638720007. The reversal of 1638720000 is 278361.

1638720000 is a `hidden beast` number, since 1 + 638 + 7 + 20 + 0 + 0 + 0 = 666.

It can be written as a sum of positive squares in 5 ways, for example, as 9144576 + 1629575424 = 3024^2 + 40368^2 .

It is a tau number, because it is divible by the number of its divisors (300).

It is not an unprimeable number, because it can be changed into a prime (1638720007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 2879716 + ... + 2880284.

Almost surely, 2^1638720000 is an apocalyptic number.

1638720000 is a gapful number since it is divisible by the number (10) 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 1638720000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2960157915).

1638720000 is an abundant number, since it is smaller than the sum of its proper divisors (4281595830).

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

1638720000 is an frugal number, since it uses more digits than its factorization.

1638720000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 613 (or 579 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 1638720000 is about 40481.1067042392. The cubic root of 1638720000 is about 1178.9668252249.

Adding to 1638720000 its reverse (278361), we get a palindrome (1638998361).

The spelling of 1638720000 in words is "one billion, six hundred thirty-eight million, seven hundred twenty thousand".