13221091728 has 240 divisors, whose sum is σ = 41978384640. Its totient is φ = 3980441088.

The previous prime is 13221091717. The next prime is 13221091747. The reversal of 13221091728 is 82719012231.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 13221091692 and 13221091701.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3429450 + ... + 3433302.

It is an arithmetic number, because the mean of its divisors is an integer number (174909936).

Almost surely, 2^13221091728 is an apocalyptic number.

13221091728 is a gapful number since it is divisible by the number (18) 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 13221091728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20989192320).

13221091728 is an abundant number, since it is smaller than the sum of its proper divisors (28757292912).

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

13221091728 is a wasteful number, since it uses less digits than its factorization.

13221091728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3943 (or 3918 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The spelling of 13221091728 in words is "thirteen billion, two hundred twenty-one million, ninety-one thousand, seven hundred twenty-eight".