8213581 has 2 divisors, whose sum is σ = 8213582. Its totient is φ = 8213580.

The previous prime is 8213549. The next prime is 8213591. The reversal of 8213581 is 1853128.

8213581 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4473225 + 3740356 = 2115^2 + 1934^2 .

It is a cyclic number.

It is not a de Polignac number, because 8213581 - 2⁵ = 8213549 is a prime.

It is a super-2 number, since 2×8213581² = 134925825687122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8213531) 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 as a sum of consecutive naturals, namely, 4106790 + 4106791.

It is an arithmetic number, because the mean of its divisors is an integer number (4106791).

Almost surely, 2^8213581 is an apocalyptic number.

It is an amenable number.

8213581 is a deficient number, since it is larger than the sum of its proper divisors (1).

8213581 is an equidigital number, since it uses as much as digits as its factorization.

8213581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1920, while the sum is 28.

The square root of 8213581 is about 2865.9345770621. The cubic root of 8213581 is about 201.7642333107.

The spelling of 8213581 in words is "eight million, two hundred thirteen thousand, five hundred eighty-one".