18931120121 has 2 divisors, whose sum is σ = 18931120122. Its totient is φ = 18931120120.

The previous prime is 18931120093. The next prime is 18931120123. The reversal of 18931120121 is 12102113981.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18508242025 + 422878096 = 136045^2 + 20564^2 .

It is an emirp because it is prime and its reverse (12102113981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18931120121 - 2⁶ = 18931120057 is a prime.

Together with 18931120123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18931120123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9465560060 + 9465560061.

It is an arithmetic number, because the mean of its divisors is an integer number (9465560061).

Almost surely, 2^18931120121 is an apocalyptic number.

It is an amenable number.

18931120121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18931120121 is an equidigital number, since it uses as much as digits as its factorization.

18931120121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 29.

The spelling of 18931120121 in words is "eighteen billion, nine hundred thirty-one million, one hundred twenty thousand, one hundred twenty-one".