8158221 has 12 divisors (see below), whose sum is σ = 12072060. Its totient is φ = 5305920.

The previous prime is 8158217. The next prime is 8158223. The reversal of 8158221 is 1228518.

8158221 is a `hidden beast` number, since 81 + 582 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 656100 + 7502121 = 810^2 + 2739^2 .

It is not a de Polignac number, because 8158221 - 2² = 8158217 is a prime.

8158221 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8158223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10686 + ... + 11423.

It is an arithmetic number, because the mean of its divisors is an integer number (1006005).

Almost surely, 2^8158221 is an apocalyptic number.

It is an amenable number.

8158221 is a deficient number, since it is larger than the sum of its proper divisors (3913839).

8158221 is a wasteful number, since it uses less digits than its factorization.

8158221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22156 (or 22153 counting only the distinct ones).

The product of its digits is 1280, while the sum is 27.

The square root of 8158221 is about 2856.2599671599. The cubic root of 8158221 is about 201.3099102784.

The spelling of 8158221 in words is "eight million, one hundred fifty-eight thousand, two hundred twenty-one".