18001121 has 2 divisors, whose sum is σ = 18001122. Its totient is φ = 18001120.

The previous prime is 18001117. The next prime is 18001153. The reversal of 18001121 is 12110081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17808400 + 192721 = 4220^2 + 439^2 .

It is a cyclic number.

It is not a de Polignac number, because 18001121 - 2² = 18001117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18001096 and 18001105.

It is not a weakly prime, because it can be changed into another prime (18003121) 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, 9000560 + 9000561.

It is an arithmetic number, because the mean of its divisors is an integer number (9000561).

Almost surely, 2^18001121 is an apocalyptic number.

It is an amenable number.

18001121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18001121 is an equidigital number, since it uses as much as digits as its factorization.

18001121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 14.

The square root of 18001121 is about 4242.7727961794. The cubic root of 18001121 is about 262.0795797730.

The spelling of 18001121 in words is "eighteen million, one thousand, one hundred twenty-one".