121815601 has 2 divisors, whose sum is σ = 121815602. Its totient is φ = 121815600.

The previous prime is 121815599. The next prime is 121815637. The reversal of 121815601 is 106518121.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 96825600 + 24990001 = 9840^2 + 4999^2 .

It is a cyclic number.

It is not a de Polignac number, because 121815601 - 2¹ = 121815599 is a prime.

Together with 121815599, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (121815641) 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, 60907800 + 60907801.

It is an arithmetic number, because the mean of its divisors is an integer number (60907801).

Almost surely, 2^121815601 is an apocalyptic number.

It is an amenable number.

121815601 is a deficient number, since it is larger than the sum of its proper divisors (1).

121815601 is an equidigital number, since it uses as much as digits as its factorization.

121815601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 25.

The square root of 121815601 is about 11037.0105100974. The cubic root of 121815601 is about 495.7175608117.

The spelling of 121815601 in words is "one hundred twenty-one million, eight hundred fifteen thousand, six hundred one".