217387555871 has 4 divisors (see below), whose sum is σ = 228829006200. Its totient is φ = 205946105544.

The previous prime is 217387555843. The next prime is 217387555901. The reversal of 217387555871 is 178555783712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 217387555871 - 2¹⁰ = 217387554847 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 217387555871.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217387555171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5720725136 + ... + 5720725173.

It is an arithmetic number, because the mean of its divisors is an integer number (57207251550).

Almost surely, 2^217387555871 is an apocalyptic number.

217387555871 is a deficient number, since it is larger than the sum of its proper divisors (11441450329).

217387555871 is a wasteful number, since it uses less digits than its factorization.

217387555871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11441450328.

The product of its digits is 16464000, while the sum is 59.

The spelling of 217387555871 in words is "two hundred seventeen billion, three hundred eighty-seven million, five hundred fifty-five thousand, eight hundred seventy-one".