121991939 has 2 divisors, whose sum is σ = 121991940. Its totient is φ = 121991938.

The previous prime is 121991921. The next prime is 121991957. The reversal of 121991939 is 939199121.

It is a balanced prime because it is at equal distance from previous prime (121991921) and next prime (121991957).

It is a cyclic number.

It is not a de Polignac number, because 121991939 - 2¹² = 121987843 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 121991939.

It is not a weakly prime, because it can be changed into another prime (121991959) 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, 60995969 + 60995970.

It is an arithmetic number, because the mean of its divisors is an integer number (60995970).

Almost surely, 2^121991939 is an apocalyptic number.

121991939 is a deficient number, since it is larger than the sum of its proper divisors (1).

121991939 is an equidigital number, since it uses as much as digits as its factorization.

121991939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39366, while the sum is 44.

The square root of 121991939 is about 11044.9961068350. The cubic root of 121991939 is about 495.9566426613.

The spelling of 121991939 in words is "one hundred twenty-one million, nine hundred ninety-one thousand, nine hundred thirty-nine".