121131991 has 2 divisors, whose sum is σ = 121131992. Its totient is φ = 121131990.

The previous prime is 121131949. The next prime is 121132001. The reversal of 121131991 is 199131121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 121131991 - 2¹⁹ = 120607703 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121131931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60565995 + 60565996.

It is an arithmetic number, because the mean of its divisors is an integer number (60565996).

Almost surely, 2^121131991 is an apocalyptic number.

121131991 is a deficient number, since it is larger than the sum of its proper divisors (1).

121131991 is an equidigital number, since it uses as much as digits as its factorization.

121131991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486, while the sum is 28.

The square root of 121131991 is about 11005.9979556604. The cubic root of 121131991 is about 494.7885244328.

The spelling of 121131991 in words is "one hundred twenty-one million, one hundred thirty-one thousand, nine hundred ninety-one".