121515109 has 2 divisors, whose sum is σ = 121515110. Its totient is φ = 121515108.

The previous prime is 121515091. The next prime is 121515137. The reversal of 121515109 is 901515121.

It is a happy number.

Together with previous prime (121515091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 121484484 + 30625 = 11022^2 + 175^2 .

It is a cyclic number.

It is not a de Polignac number, because 121515109 - 2⁵ = 121515077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121515139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60757554 + 60757555.

It is an arithmetic number, because the mean of its divisors is an integer number (60757555).

Almost surely, 2^121515109 is an apocalyptic number.

It is an amenable number.

121515109 is a deficient number, since it is larger than the sum of its proper divisors (1).

121515109 is an equidigital number, since it uses as much as digits as its factorization.

121515109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450, while the sum is 25.

The square root of 121515109 is about 11023.3891793767. The cubic root of 121515109 is about 495.3096168614.

The spelling of 121515109 in words is "one hundred twenty-one million, five hundred fifteen thousand, one hundred nine".