18391125121 has 2 divisors, whose sum is σ = 18391125122. Its totient is φ = 18391125120.

The previous prime is 18391125097. The next prime is 18391125157. The reversal of 18391125121 is 12152119381.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12950440000 + 5440685121 = 113800^2 + 73761^2 .

It is a cyclic number.

It is not a de Polignac number, because 18391125121 - 2¹³ = 18391116929 is a prime.

It is not a weakly prime, because it can be changed into another prime (18391125161) 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, 9195562560 + 9195562561.

It is an arithmetic number, because the mean of its divisors is an integer number (9195562561).

Almost surely, 2^18391125121 is an apocalyptic number.

It is an amenable number.

18391125121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18391125121 is an equidigital number, since it uses as much as digits as its factorization.

18391125121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 34.

The spelling of 18391125121 in words is "eighteen billion, three hundred ninety-one million, one hundred twenty-five thousand, one hundred twenty-one".