221306 has 16 divisors (see below), whose sum is σ = 368064. Its totient is φ = 99264.

The previous prime is 221303. The next prime is 221311. The reversal of 221306 is 603122.

221306 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (221303) 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, 641 + ... + 923.

It is an arithmetic number, because the mean of its divisors is an integer number (23004).

2²²¹³⁰⁶ is an apocalyptic number.

221306 is a deficient number, since it is larger than the sum of its proper divisors (146758).

221306 is a wasteful number, since it uses less digits than its factorization.

221306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 221306 is about 470.4317166178. The cubic root of 221306 is about 60.4873274461.

Adding to 221306 its reverse (603122), we get a palindrome (824428).

The spelling of 221306 in words is "two hundred twenty-one thousand, three hundred six".