8442621221 has 4 divisors (see below), whose sum is σ = 8474006700. Its totient is φ = 8411235744.

The previous prime is 8442621197. The next prime is 8442621223. The reversal of 8442621221 is 1221262448.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2203833025 + 6238788196 = 46945^2 + 78986^2 .

It is a cyclic number.

It is not a de Polignac number, because 8442621221 - 2²⁶ = 8375512357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8442621223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15692336 + ... + 15692873.

It is an arithmetic number, because the mean of its divisors is an integer number (2118501675).

Almost surely, 2^8442621221 is an apocalyptic number.

It is an amenable number.

8442621221 is a deficient number, since it is larger than the sum of its proper divisors (31385479).

8442621221 is a wasteful number, since it uses less digits than its factorization.

8442621221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31385478.

The product of its digits is 12288, while the sum is 32.

The square root of 8442621221 is about 91883.7375219358. The cubic root of 8442621221 is about 2036.2250145491.

Adding to 8442621221 its reverse (1221262448), we get a palindrome (9663883669).

The spelling of 8442621221 in words is "eight billion, four hundred forty-two million, six hundred twenty-one thousand, two hundred twenty-one".