21336553728 has 648 divisors, whose sum is σ = 78153566400. Its totient is φ = 5576159232.

The previous prime is 21336553697. The next prime is 21336553729. The reversal of 21336553728 is 82735563312.

21336553728 is a `hidden beast` number, since 2 + 1 + 33 + 65 + 537 + 28 = 666.

Its product of digits (907200) is a multiple of the sum of its prime divisors (60).

It is not an unprimeable number, because it can be changed into a prime (21336553729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 735743218 + ... + 735743246.

Almost surely, 2^21336553728 is an apocalyptic number.

21336553728 is a gapful number since it is divisible by the number (28) 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 21336553728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39076783200).

21336553728 is an abundant number, since it is smaller than the sum of its proper divisors (56817012672).

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

21336553728 is an frugal number, since it uses more digits than its factorization.

21336553728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 60 counting only the distinct ones).

The product of its digits is 907200, while the sum is 45.

The spelling of 21336553728 in words is "twenty-one billion, three hundred thirty-six million, five hundred fifty-three thousand, seven hundred twenty-eight".