221530306 has 8 divisors (see below), whose sum is σ = 334216764. Its totient is φ = 110124720.

The previous prime is 221530271. The next prime is 221530307. The reversal of 221530306 is 603035122.

It can be written as a sum of positive squares in 2 ways, for example, as 216354681 + 5175625 = 14709^2 + 2275^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×221530306³ (a number of 26 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (221530307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 319785 + ... + 320476.

Almost surely, 2^221530306 is an apocalyptic number.

221530306 is a deficient number, since it is larger than the sum of its proper divisors (112686458).

221530306 is a wasteful number, since it uses less digits than its factorization.

221530306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640436.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 221530306 is about 14883.8941812954. The cubic root of 221530306 is about 605.0775630812.

Adding to 221530306 its reverse (603035122), we get a palindrome (824565428).

The spelling of 221530306 in words is "two hundred twenty-one million, five hundred thirty thousand, three hundred six".