121561562509 has 2 divisors, whose sum is σ = 121561562510. Its totient is φ = 121561562508.

The previous prime is 121561562503. The next prime is 121561562543. The reversal of 121561562509 is 905265165121.

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., 66628515625 + 54933046884 = 258125^2 + 234378^2 .

It is a cyclic number.

It is not a de Polignac number, because 121561562509 - 2³ = 121561562501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121561562501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60780781254 + 60780781255.

It is an arithmetic number, because the mean of its divisors is an integer number (60780781255).

Almost surely, 2^121561562509 is an apocalyptic number.

It is an amenable number.

121561562509 is a deficient number, since it is larger than the sum of its proper divisors (1).

121561562509 is an equidigital number, since it uses as much as digits as its factorization.

121561562509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162000, while the sum is 43.

The spelling of 121561562509 in words is "one hundred twenty-one billion, five hundred sixty-one million, five hundred sixty-two thousand, five hundred nine".