230721 has 4 divisors (see below), whose sum is σ = 307632. Its totient is φ = 153812.

The previous prime is 230719. The next prime is 230729. The reversal of 230721 is 127032.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 230721 - 2¹ = 230719 is a prime.

It is a D-number.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

230721 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 230721.

It is not an unprimeable number, because it can be changed into a prime (230729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38451 + ... + 38456.

It is an arithmetic number, because the mean of its divisors is an integer number (76908).

2²³⁰⁷²¹ is an apocalyptic number.

It is an amenable number.

230721 is a deficient number, since it is larger than the sum of its proper divisors (76911).

230721 is an equidigital number, since it uses as much as digits as its factorization.

230721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76910.

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 230721 is about 480.3342586158. The cubic root of 230721 is about 61.3332119038. Note that the first 3 decimals are identical.

Adding to 230721 its reverse (127032), we get a palindrome (357753).

The spelling of 230721 in words is "two hundred thirty thousand, seven hundred twenty-one".