1091581 has 2 divisors, whose sum is σ = 1091582. Its totient is φ = 1091580.

The previous prime is 1091561. The next prime is 1091591. The reversal of 1091581 is 1851901.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 648025 + 443556 = 805^2 + 666^2 .

It is an emirp because it is prime and its reverse (1851901) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1091581 - 2⁵ = 1091549 is a prime.

It is a super-2 number, since 2×1091581² = 2383098159122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1091521) 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, 545790 + 545791.

It is an arithmetic number, because the mean of its divisors is an integer number (545791).

2^1091581 is an apocalyptic number.

It is an amenable number.

1091581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1091581 is an equidigital number, since it uses as much as digits as its factorization.

1091581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 25.

The square root of 1091581 is about 1044.7875382105. The cubic root of 1091581 is about 102.9639802414.

The spelling of 1091581 in words is "one million, ninety-one thousand, five hundred eighty-one".