121391111 has 2 divisors, whose sum is σ = 121391112. Its totient is φ = 121391110.

The previous prime is 121391099. The next prime is 121391113. The reversal of 121391111 is 111193121.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 121391111 - 2²⁶ = 54282247 is a prime.

It is a Sophie Germain prime.

Together with 121391113, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121391113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60695555 + 60695556.

It is an arithmetic number, because the mean of its divisors is an integer number (60695556).

Almost surely, 2^121391111 is an apocalyptic number.

121391111 is a deficient number, since it is larger than the sum of its proper divisors (1).

121391111 is an equidigital number, since it uses as much as digits as its factorization.

121391111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54, while the sum is 20.

The square root of 121391111 is about 11017.7634300252. The cubic root of 121391111 is about 495.1410828000.

The spelling of 121391111 in words is "one hundred twenty-one million, three hundred ninety-one thousand, one hundred eleven".