8121508221 has 4 divisors (see below), whose sum is σ = 10828677632. Its totient is φ = 5414338812.

The previous prime is 8121508211. The next prime is 8121508259. The reversal of 8121508221 is 1228051218.

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 not a de Polignac number, because 8121508221 - 2¹⁰ = 8121507197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8121508211) 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, 1353584701 + ... + 1353584706.

It is an arithmetic number, because the mean of its divisors is an integer number (2707169408).

Almost surely, 2^8121508221 is an apocalyptic number.

It is an amenable number.

8121508221 is a deficient number, since it is larger than the sum of its proper divisors (2707169411).

8121508221 is a wasteful number, since it uses less digits than its factorization.

8121508221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2707169410.

The product of its (nonzero) digits is 2560, while the sum is 30.

The square root of 8121508221 is about 90119.4109002051. The cubic root of 8121508221 is about 2010.0748485778.

Adding to 8121508221 its reverse (1228051218), we get a palindrome (9349559439).

The spelling of 8121508221 in words is "eight billion, one hundred twenty-one million, five hundred eight thousand, two hundred twenty-one".