217206066 has 64 divisors (see below), whose sum is σ = 565180416. Its totient is φ = 53961600.

The previous prime is 217206019. The next prime is 217206071. The reversal of 217206066 is 660602712.

217206066 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 406 + ... + 20846.

It is an arithmetic number, because the mean of its divisors is an integer number (8830944).

Almost surely, 2^217206066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217206066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (282590208).

217206066 is an abundant number, since it is smaller than the sum of its proper divisors (347974350).

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

217206066 is a wasteful number, since it uses less digits than its factorization.

217206066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20487.

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 217206066 is about 14737.9125387553. The cubic root of 217206066 is about 601.1146557331.

Adding to 217206066 its reverse (660602712), we get a palindrome (877808778).

The spelling of 217206066 in words is "two hundred seventeen million, two hundred six thousand, sixty-six".