218619221 has 4 divisors (see below), whose sum is σ = 219827244. Its totient is φ = 217411200.

The previous prime is 218619217. The next prime is 218619241. The reversal of 218619221 is 122916812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11662225 + 206956996 = 3415^2 + 14386^2 .

It is a cyclic number.

It is not a de Polignac number, because 218619221 - 2² = 218619217 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 (218619241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 603740 + ... + 604101.

It is an arithmetic number, because the mean of its divisors is an integer number (54956811).

Almost surely, 2^218619221 is an apocalyptic number.

It is an amenable number.

218619221 is a deficient number, since it is larger than the sum of its proper divisors (1208023).

218619221 is a wasteful number, since it uses less digits than its factorization.

218619221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208022.

The product of its digits is 3456, while the sum is 32.

The square root of 218619221 is about 14785.7776596295. Note that the first 3 decimals coincide. The cubic root of 218619221 is about 602.4154674423.

The spelling of 218619221 in words is "two hundred eighteen million, six hundred nineteen thousand, two hundred twenty-one".