18120581 has 2 divisors, whose sum is σ = 18120582. Its totient is φ = 18120580.

The previous prime is 18120569. The next prime is 18120607. The reversal of 18120581 is 18502181.

It is an a-pointer prime, because the next prime (18120607) can be obtained adding 18120581 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18062500 + 58081 = 4250^2 + 241^2 .

It is a cyclic number.

It is not a de Polignac number, because 18120581 - 2⁶ = 18120517 is a prime.

It is a super-4 number, since 4×18120581⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18120581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18128581) 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, 9060290 + 9060291.

It is an arithmetic number, because the mean of its divisors is an integer number (9060291).

Almost surely, 2^18120581 is an apocalyptic number.

It is an amenable number.

18120581 is a deficient number, since it is larger than the sum of its proper divisors (1).

18120581 is an equidigital number, since it uses as much as digits as its factorization.

18120581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 26.

The square root of 18120581 is about 4256.8275746147. The cubic root of 18120581 is about 262.6580442069.

The spelling of 18120581 in words is "eighteen million, one hundred twenty thousand, five hundred eighty-one".