121751556517 has 4 divisors (see below), whose sum is σ = 121752368140. Its totient is φ = 121750744896.

The previous prime is 121751556491. The next prime is 121751556523. The reversal of 121751556517 is 715655157121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 715655157121 = 173629 ⋅4121749.

It can be written as a sum of positive squares in 2 ways, for example, as 55945967841 + 65805588676 = 236529^2 + 256526^2 .

It is a cyclic number.

It is not a de Polignac number, because 121751556517 - 2⁷ = 121751556389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121751556527) 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 3 ways as a sum of consecutive naturals, for example, 107892 + ... + 505117.

It is an arithmetic number, because the mean of its divisors is an integer number (30438092035).

Almost surely, 2^121751556517 is an apocalyptic number.

It is an amenable number.

121751556517 is a deficient number, since it is larger than the sum of its proper divisors (811623).

121751556517 is an equidigital number, since it uses as much as digits as its factorization.

121751556517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811622.

The product of its digits is 367500, while the sum is 46.

The spelling of 121751556517 in words is "one hundred twenty-one billion, seven hundred fifty-one million, five hundred fifty-six thousand, five hundred seventeen".