8661581 has 2 divisors, whose sum is σ = 8661582. Its totient is φ = 8661580.

The previous prime is 8661577. The next prime is 8661623. The reversal of 8661581 is 1851668.

8661581 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8649481 + 12100 = 2941^2 + 110^2 .

It is a cyclic number.

It is not a de Polignac number, because 8661581 - 2² = 8661577 is a prime.

It is a super-2 number, since 2×8661581² = 150045970839122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8661571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4330790 + 4330791.

It is an arithmetic number, because the mean of its divisors is an integer number (4330791).

Almost surely, 2^8661581 is an apocalyptic number.

It is an amenable number.

8661581 is a deficient number, since it is larger than the sum of its proper divisors (1).

8661581 is an equidigital number, since it uses as much as digits as its factorization.

8661581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 35.

The square root of 8661581 is about 2943.0564044884. The cubic root of 8661581 is about 205.3678187310.

The spelling of 8661581 in words is "eight million, six hundred sixty-one thousand, five hundred eighty-one".