217879758666 has 12 divisors (see below), whose sum is σ = 472072810482. Its totient is φ = 72626586216.

The previous prime is 217879758631. The next prime is 217879758671. The reversal of 217879758666 is 666857978712.

217879758666 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., 200364559641 + 17515199025 = 447621^2 + 132345^2 .

It is a junction number, because it is equal to n+sod(n) for n = 217879758594 and 217879758603.

It is an unprimeable number.

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, 6052215501 + ... + 6052215536.

Almost surely, 2^217879758666 is an apocalyptic number.

217879758666 is an abundant number, since it is smaller than the sum of its proper divisors (254193051816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217879758666 is a wasteful number, since it uses less digits than its factorization.

217879758666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12104431045 (or 12104431042 counting only the distinct ones).

The product of its digits is 426746880, while the sum is 72.

The spelling of 217879758666 in words is "two hundred seventeen billion, eight hundred seventy-nine million, seven hundred fifty-eight thousand, six hundred sixty-six".