21084421600 has 216 divisors, whose sum is σ = 59271472008. Its totient is φ = 7262438400.

The previous prime is 21084421597. The next prime is 21084421601. The reversal of 21084421600 is 612448012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21084421601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3173482 + ... + 3180118.

It is an arithmetic number, because the mean of its divisors is an integer number (274404963).

Almost surely, 2^21084421600 is an apocalyptic number.

21084421600 is a gapful number since it is divisible by the number (20) 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 21084421600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29635736004).

21084421600 is an abundant number, since it is smaller than the sum of its proper divisors (38187050408).

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

21084421600 is a wasteful number, since it uses less digits than its factorization.

21084421600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6706 (or 6674 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

Adding to 21084421600 its reverse (612448012), we get a palindrome (21696869612).

The spelling of 21084421600 in words is "twenty-one billion, eighty-four million, four hundred twenty-one thousand, six hundred".