121556657601 has 24 divisors (see below), whose sum is σ = 176899515624. Its totient is φ = 80429856000.

The previous prime is 121556657567. The next prime is 121556657617. The reversal of 121556657601 is 106756655121.

It is a happy number.

121556657601 is a `hidden beast` number, since 1 + 2 + 15 + 5 + 66 + 576 + 0 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 18915876225 + 102640781376 = 137535^2 + 320376^2 .

It is not a de Polignac number, because 121556657601 - 2¹⁰ = 121556656577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121556657801) 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 in 23 ways as a sum of consecutive naturals, for example, 10475935 + ... + 10487531.

It is an arithmetic number, because the mean of its divisors is an integer number (7370813151).

Almost surely, 2^121556657601 is an apocalyptic number.

It is an amenable number.

121556657601 is a deficient number, since it is larger than the sum of its proper divisors (55342858023).

121556657601 is a wasteful number, since it uses less digits than its factorization.

121556657601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20241 (or 20238 counting only the distinct ones).

The product of its (nonzero) digits is 378000, while the sum is 45.

The spelling of 121556657601 in words is "one hundred twenty-one billion, five hundred fifty-six million, six hundred fifty-seven thousand, six hundred one".