221561221 has 8 divisors (see below), whose sum is σ = 268107840. Its totient is φ = 178738368.

The previous prime is 221561213. The next prime is 221561233. The reversal of 221561221 is 122165122.

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

It is a cyclic number.

It is not a de Polignac number, because 221561221 - 2³ = 221561213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221561192 and 221561201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221561201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 930811 + ... + 931048.

It is an arithmetic number, because the mean of its divisors is an integer number (33513480).

Almost surely, 2^221561221 is an apocalyptic number.

It is an amenable number.

221561221 is a deficient number, since it is larger than the sum of its proper divisors (46546619).

221561221 is a wasteful number, since it uses less digits than its factorization.

221561221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1861883.

The product of its digits is 480, while the sum is 22.

The square root of 221561221 is about 14884.9326837578. The cubic root of 221561221 is about 605.1057083692.

It can be divided in two parts, 2215 and 61221, that added together give a palindrome (63436).

The spelling of 221561221 in words is "two hundred twenty-one million, five hundred sixty-one thousand, two hundred twenty-one".