8181581 has 2 divisors, whose sum is σ = 8181582. Its totient is φ = 8181580.

The previous prime is 8181577. The next prime is 8181587. The reversal of 8181581 is 1851818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4818025 + 3363556 = 2195^2 + 1834^2 .

It is a cyclic number.

It is not a de Polignac number, because 8181581 - 2² = 8181577 is a prime.

It is a super-2 number, since 2×8181581² = 133876535319122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8181587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4090790 + 4090791.

It is an arithmetic number, because the mean of its divisors is an integer number (4090791).

Almost surely, 2^8181581 is an apocalyptic number.

It is an amenable number.

8181581 is a deficient number, since it is larger than the sum of its proper divisors (1).

8181581 is an equidigital number, since it uses as much as digits as its factorization.

8181581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2560, while the sum is 32.

The square root of 8181581 is about 2860.3463077047. The cubic root of 8181581 is about 201.5018687215.

The spelling of 8181581 in words is "eight million, one hundred eighty-one thousand, five hundred eighty-one".