218201221 has 16 divisors (see below), whose sum is σ = 261410688. Its totient is φ = 178214400.

The previous prime is 218201201. The next prime is 218201231. The reversal of 218201221 is 122102812.

It is not a de Polignac number, because 218201221 - 2¹³ = 218193029 is a prime.

It is a super-2 number, since 2×218201221² = 95223545691781682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218201201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3501 + ... + 21181.

It is an arithmetic number, because the mean of its divisors is an integer number (16338168).

Almost surely, 2^218201221 is an apocalyptic number.

It is an amenable number.

218201221 is a deficient number, since it is larger than the sum of its proper divisors (43209467).

218201221 is a wasteful number, since it uses less digits than its factorization.

218201221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17772.

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

The square root of 218201221 is about 14771.6356914189. The cubic root of 218201221 is about 602.0312829812.

The spelling of 218201221 in words is "two hundred eighteen million, two hundred one thousand, two hundred twenty-one".