121839561 has 12 divisors (see below), whose sum is σ = 186343092. Its totient is φ = 76448256.

The previous prime is 121839551. The next prime is 121839569. The reversal of 121839561 is 165938121.

121839561 is a `hidden beast` number, since 12 + 1 + 83 + 9 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 83832336 + 38007225 = 9156^2 + 6165^2 .

It is not a de Polignac number, because 121839561 - 2⁹ = 121839049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121839569) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 398016 + ... + 398321.

It is an arithmetic number, because the mean of its divisors is an integer number (15528591).

Almost surely, 2^121839561 is an apocalyptic number.

It is an amenable number.

121839561 is a deficient number, since it is larger than the sum of its proper divisors (64503531).

121839561 is a wasteful number, since it uses less digits than its factorization.

121839561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 796360 (or 796357 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 121839561 is about 11038.0958955791. The cubic root of 121839561 is about 495.7500596980.

The spelling of 121839561 in words is "one hundred twenty-one million, eight hundred thirty-nine thousand, five hundred sixty-one".