221121216 has 42 divisors (see below), whose sum is σ = 633805692. Its totient is φ = 73706880.

The previous prime is 221121209. The next prime is 221121217. The reversal of 221121216 is 612121122.

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

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is not an unprimeable number, because it can be changed into a prime (221121217) 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 5 ways as a sum of consecutive naturals, for example, 191370 + ... + 192521.

Almost surely, 2^221121216 is an apocalyptic number.

It is an amenable number.

221121216 is an abundant number, since it is smaller than the sum of its proper divisors (412684476).

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

221121216 is a wasteful number, since it uses less digits than its factorization.

221121216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383909 (or 383896 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 221121216 is about 14870.1451237034. The cubic root of 221121216 is about 604.7048771202.

Adding to 221121216 its reverse (612121122), we get a palindrome (833242338).

The spelling of 221121216 in words is "two hundred twenty-one million, one hundred twenty-one thousand, two hundred sixteen".