221206566 has 16 divisors (see below), whose sum is σ = 505615104. Its totient is φ = 63201864.

The previous prime is 221206561. The next prime is 221206591. The reversal of 221206566 is 665602122.

221206566 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221206561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2633370 + ... + 2633453.

It is an arithmetic number, because the mean of its divisors is an integer number (31600944).

Almost surely, 2^221206566 is an apocalyptic number.

221206566 is an abundant number, since it is smaller than the sum of its proper divisors (284408538).

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

221206566 is a wasteful number, since it uses less digits than its factorization.

221206566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5266835.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 221206566 is about 14873.0146910436. The cubic root of 221206566 is about 604.7826699301.

Adding to 221206566 its reverse (665602122), we get a palindrome (886808688).

The spelling of 221206566 in words is "two hundred twenty-one million, two hundred six thousand, five hundred sixty-six".