121553505817 has 2 divisors, whose sum is σ = 121553505818. Its totient is φ = 121553505816.

The previous prime is 121553505793. The next prime is 121553505869. The reversal of 121553505817 is 718505355121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 110718569536 + 10834936281 = 332744^2 + 104091^2 .

It is an emirp because it is prime and its reverse (718505355121) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121553505817 is a prime.

It is not a weakly prime, because it can be changed into another prime (121553505217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60776752908 + 60776752909.

It is an arithmetic number, because the mean of its divisors is an integer number (60776752909).

Almost surely, 2^121553505817 is an apocalyptic number.

It is an amenable number.

121553505817 is a deficient number, since it is larger than the sum of its proper divisors (1).

121553505817 is an equidigital number, since it uses as much as digits as its factorization.

121553505817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210000, while the sum is 43.

The spelling of 121553505817 in words is "one hundred twenty-one billion, five hundred fifty-three million, five hundred five thousand, eight hundred seventeen".