8724221 has 6 divisors (see below), whose sum is σ = 9589566. Its totient is φ = 7931000.

The previous prime is 8724181. The next prime is 8724223. The reversal of 8724221 is 1224278.

8724221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 6180196 + 2544025 = 2486^2 + 1595^2 .

It is not a de Polignac number, because 8724221 - 2¹⁴ = 8707837 is a prime.

It is a super-2 number, since 2×8724221² = 152224064113682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8724223) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35930 + ... + 36171.

It is an arithmetic number, because the mean of its divisors is an integer number (1598261).

Almost surely, 2^8724221 is an apocalyptic number.

It is an amenable number.

8724221 is a deficient number, since it is larger than the sum of its proper divisors (865345).

8724221 is a wasteful number, since it uses less digits than its factorization.

8724221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72123 (or 72112 counting only the distinct ones).

The product of its digits is 1792, while the sum is 26.

The square root of 8724221 is about 2953.6792310608. The cubic root of 8724221 is about 205.8616990453.

Adding to 8724221 its reverse (1224278), we get a palindrome (9948499).

The spelling of 8724221 in words is "eight million, seven hundred twenty-four thousand, two hundred twenty-one".