217121913873 has 6 divisors (see below), whose sum is σ = 313620542274. Its totient is φ = 144747942576.

The previous prime is 217121913847. The next prime is 217121913881. The reversal of 217121913873 is 378319121712.

217121913873 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 212049198144 + 5072715729 = 460488^2 + 71223^2 .

It is not a de Polignac number, because 217121913873 - 2²⁵ = 217088359441 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (217121913893) 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 5 ways as a sum of consecutive naturals, for example, 12062328540 + ... + 12062328557.

It is an arithmetic number, because the mean of its divisors is an integer number (52270090379).

Almost surely, 2^217121913873 is an apocalyptic number.

It is an amenable number.

217121913873 is a deficient number, since it is larger than the sum of its proper divisors (96498628401).

217121913873 is a wasteful number, since it uses less digits than its factorization.

217121913873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24124657103 (or 24124657100 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The spelling of 217121913873 in words is "two hundred seventeen billion, one hundred twenty-one million, nine hundred thirteen thousand, eight hundred seventy-three".