121115561 has 16 divisors (see below), whose sum is σ = 142312320. Its totient is φ = 100932480.

The previous prime is 121115549. The next prime is 121115567. The reversal of 121115561 is 165511121.

It is a cyclic number.

It is not a de Polignac number, because 121115561 - 2²⁶ = 54006697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121115567) 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 in 15 ways as a sum of consecutive naturals, for example, 36410 + ... + 39596.

It is an arithmetic number, because the mean of its divisors is an integer number (8894520).

Almost surely, 2^121115561 is an apocalyptic number.

It is an amenable number.

121115561 is a deficient number, since it is larger than the sum of its proper divisors (21196759).

121115561 is an equidigital number, since it uses as much as digits as its factorization.

121115561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3344.

The product of its digits is 300, while the sum is 23.

The square root of 121115561 is about 11005.2515191612. The cubic root of 121115561 is about 494.7661528501.

Adding to 121115561 its reverse (165511121), we get a palindrome (286626682).

The spelling of 121115561 in words is "one hundred twenty-one million, one hundred fifteen thousand, five hundred sixty-one".