2828320721 has 4 divisors (see below), whose sum is σ = 2829993012. Its totient is φ = 2826648432.

The previous prime is 2828320711. The next prime is 2828320727. The reversal of 2828320721 is 1270238282.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1270238282 = 2 ⋅635119141.

It can be written as a sum of positive squares in 2 ways, for example, as 1478787025 + 1349533696 = 38455^2 + 36736^2 .

It is a cyclic number.

It is not a de Polignac number, because 2828320721 - 2²⁶ = 2761211857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2828320727) 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 3 ways as a sum of consecutive naturals, for example, 833606 + ... + 836991.

It is an arithmetic number, because the mean of its divisors is an integer number (707498253).

Almost surely, 2^2828320721 is an apocalyptic number.

It is an amenable number.

2828320721 is a deficient number, since it is larger than the sum of its proper divisors (1672291).

2828320721 is a wasteful number, since it uses less digits than its factorization.

2828320721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1672290.

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 2828320721 is about 53181.9586043989. The cubic root of 2828320721 is about 1414.1958281930.

The spelling of 2828320721 in words is "two billion, eight hundred twenty-eight million, three hundred twenty thousand, seven hundred twenty-one".