8721 has 16 divisors (see below), whose sum is σ = 14400. Its totient is φ = 5184.

The previous prime is 8719. The next prime is 8731. The reversal of 8721 is 1278.

8721 is nontrivially palindromic in base 2.

It is not a de Polignac number, because 8721 - 2¹ = 8719 is a prime.

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

It is a Curzon number.

It is a nialpdrome in base 10 and base 16.

It is a zygodrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 8694 and 8703.

It is not an unprimeable number, because it can be changed into a prime (8731) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 450 + ... + 468.

It is an arithmetic number, because the mean of its divisors is an integer number (900).

It is an amenable number.

8721 is a deficient number, since it is larger than the sum of its proper divisors (5679).

8721 is a wasteful number, since it uses less digits than its factorization.

8721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45 (or 39 counting only the distinct ones).

The product of its digits is 112, while the sum is 18.

The square root of 8721 is about 93.3862944976. The cubic root of 8721 is about 20.5836361075.

Adding to 8721 its reverse (1278), we get a palindrome (9999).

It can be divided in two parts, 8 and 721, that added together give a 6-th power (729 = 3⁶).

The spelling of 8721 in words is "eight thousand, seven hundred twenty-one".