221221121 has 4 divisors (see below), whose sum is σ = 241332144. Its totient is φ = 201110100.

The previous prime is 221221097. The next prime is 221221127. The reversal of 221221121 is 121122122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221221121 - 2¹⁸ = 220958977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221221096 and 221221105.

It is not an unprimeable number, because it can be changed into a prime (221221127) 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, 10055495 + ... + 10055516.

It is an arithmetic number, because the mean of its divisors is an integer number (60333036).

Almost surely, 2^221221121 is an apocalyptic number.

It is an amenable number.

221221121 is a deficient number, since it is larger than the sum of its proper divisors (20111023).

221221121 is a wasteful number, since it uses less digits than its factorization.

221221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20111022.

The product of its digits is 32, while the sum is 14.

The square root of 221221121 is about 14873.5039919987. The cubic root of 221221121 is about 604.7959341818.

Adding to 221221121 its reverse (121122122), we get a palindrome (342343243).

The spelling of 221221121 in words is "two hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".