220181221 has 4 divisors (see below), whose sum is σ = 237118252. Its totient is φ = 203244192.

The previous prime is 220181207. The next prime is 220181237. The reversal of 220181221 is 122181022.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122181022 = 2 ⋅61090511.

It can be written as a sum of positive squares in 2 ways, for example, as 56085121 + 164096100 = 7489^2 + 12810^2 .

It is a cyclic number.

It is not a de Polignac number, because 220181221 - 2¹¹ = 220179173 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220181201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8468496 + ... + 8468521.

It is an arithmetic number, because the mean of its divisors is an integer number (59279563).

Almost surely, 2^220181221 is an apocalyptic number.

It is an amenable number.

220181221 is a deficient number, since it is larger than the sum of its proper divisors (16937031).

220181221 is a wasteful number, since it uses less digits than its factorization.

220181221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16937030.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 220181221 is about 14838.5046753371. The cubic root of 220181221 is about 603.8467852903.

The spelling of 220181221 in words is "two hundred twenty million, one hundred eighty-one thousand, two hundred twenty-one".