1181581 has 2 divisors, whose sum is σ = 1181582. Its totient is φ = 1181580.

The previous prime is 1181573. The next prime is 1181611. The reversal of 1181581 is 1851811.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1177225 + 4356 = 1085^2 + 66^2 .

It is a cyclic number.

It is not a de Polignac number, because 1181581 - 2³ = 1181573 is a prime.

It is a super-2 number, since 2×1181581² = 2792267319122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1181501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 590790 + 590791.

It is an arithmetic number, because the mean of its divisors is an integer number (590791).

2^1181581 is an apocalyptic number.

It is an amenable number.

1181581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1181581 is an equidigital number, since it uses as much as digits as its factorization.

1181581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 25.

The square root of 1181581 is about 1087.0055197652. The cubic root of 1181581 is about 105.7193537346.

The spelling of 1181581 in words is "one million, one hundred eighty-one thousand, five hundred eighty-one".