121689109 has 2 divisors, whose sum is σ = 121689110. Its totient is φ = 121689108.

The previous prime is 121689037. The next prime is 121689137. The reversal of 121689109 is 901986121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91680625 + 30008484 = 9575^2 + 5478^2 .

It is a cyclic number.

It is not a de Polignac number, because 121689109 - 2¹⁵ = 121656341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121689409) 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, 60844554 + 60844555.

It is an arithmetic number, because the mean of its divisors is an integer number (60844555).

Almost surely, 2^121689109 is an apocalyptic number.

It is an amenable number.

121689109 is a deficient number, since it is larger than the sum of its proper divisors (1).

121689109 is an equidigital number, since it uses as much as digits as its factorization.

121689109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 37.

The square root of 121689109 is about 11031.2786656851. The cubic root of 121689109 is about 495.5459188065.

The spelling of 121689109 in words is "one hundred twenty-one million, six hundred eighty-nine thousand, one hundred nine".