330721 has 2 divisors, whose sum is σ = 330722. Its totient is φ = 330720.

The previous prime is 330719. The next prime is 330731. The reversal of 330721 is 127033.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190096 + 140625 = 436^2 + 375^2 .

It is an emirp because it is prime and its reverse (127033) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 330721 - 2¹ = 330719 is a prime.

Together with 330719, it forms a pair of twin primes.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 330695 and 330704.

It is not a weakly prime, because it can be changed into another prime (330731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165360 + 165361.

It is an arithmetic number, because the mean of its divisors is an integer number (165361).

2³³⁰⁷²¹ is an apocalyptic number.

It is an amenable number.

330721 is a deficient number, since it is larger than the sum of its proper divisors (1).

330721 is an equidigital number, since it uses as much as digits as its factorization.

330721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 126, while the sum is 16.

The square root of 330721 is about 575.0834722021. The cubic root of 330721 is about 69.1545231177.

Adding to 330721 its reverse (127033), we get a palindrome (457754).

The spelling of 330721 in words is "three hundred thirty thousand, seven hundred twenty-one".