221221206 has 20 divisors (see below), whose sum is σ = 495699732. Its totient is φ = 73740348.

The previous prime is 221221127. The next prime is 221221213. The reversal of 221221206 is 602122122.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 682620 + ... + 682943.

Almost surely, 2^221221206 is an apocalyptic number.

221221206 is an abundant number, since it is smaller than the sum of its proper divisors (274478526).

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

221221206 is a wasteful number, since it uses less digits than its factorization.

221221206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1365577 (or 1365568 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 221221206 is about 14873.5068494286. The cubic root of 221221206 is about 604.7960116423.

Adding to 221221206 its reverse (602122122), we get a palindrome (823343328).

The spelling of 221221206 in words is "two hundred twenty-one million, two hundred twenty-one thousand, two hundred six".