7321321728 has 864 divisors, whose sum is σ = 28284512256. Its totient is φ = 1839366144.

The previous prime is 7321321717. The next prime is 7321321729. The reversal of 7321321728 is 8271231237.

7321321728 is a `hidden beast` number, since 7 + 321 + 321 + 7 + 2 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

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

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

It is a junction number, because it is equal to n+sod(n) for n = 7321321692 and 7321321701.

It is not an unprimeable number, because it can be changed into a prime (7321321729) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 170263275 + ... + 170263317.

It is an arithmetic number, because the mean of its divisors is an integer number (32736704).

Almost surely, 2^7321321728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7321321728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14142256128).

7321321728 is an abundant number, since it is smaller than the sum of its proper divisors (20963190528).

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

7321321728 is a wasteful number, since it uses less digits than its factorization.

7321321728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 95 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 7321321728 is about 85564.7224503183. The cubic root of 7321321728 is about 1941.7642335037.

The spelling of 7321321728 in words is "seven billion, three hundred twenty-one million, three hundred twenty-one thousand, seven hundred twenty-eight".