18078121 has 2 divisors, whose sum is σ = 18078122. Its totient is φ = 18078120.

The previous prime is 18078113. The next prime is 18078149. The reversal of 18078121 is 12187081.

It is an a-pointer prime, because the next prime (18078149) can be obtained adding 18078121 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14707225 + 3370896 = 3835^2 + 1836^2 .

It is a cyclic number.

It is not a de Polignac number, because 18078121 - 2³ = 18078113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18078121.

It is not a weakly prime, because it can be changed into another prime (18078521) 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, 9039060 + 9039061.

It is an arithmetic number, because the mean of its divisors is an integer number (9039061).

Almost surely, 2^18078121 is an apocalyptic number.

It is an amenable number.

18078121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18078121 is an equidigital number, since it uses as much as digits as its factorization.

18078121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 18078121 is about 4251.8373675389. The cubic root of 18078121 is about 262.4527310200.

The spelling of 18078121 in words is "eighteen million, seventy-eight thousand, one hundred twenty-one".