18561091 has 2 divisors, whose sum is σ = 18561092. Its totient is φ = 18561090.

The previous prime is 18561083. The next prime is 18561107. The reversal of 18561091 is 19016581.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18561091 - 2³ = 18561083 is a prime.

It is a super-2 number, since 2×18561091² = 689028198220562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18561001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9280545 + 9280546.

It is an arithmetic number, because the mean of its divisors is an integer number (9280546).

Almost surely, 2^18561091 is an apocalyptic number.

18561091 is a deficient number, since it is larger than the sum of its proper divisors (1).

18561091 is an equidigital number, since it uses as much as digits as its factorization.

18561091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 18561091 is about 4308.2584648556. The cubic root of 18561091 is about 264.7694256388.

The spelling of 18561091 in words is "eighteen million, five hundred sixty-one thousand, ninety-one".