221242121 has 8 divisors (see below), whose sum is σ = 222697800. Its totient is φ = 219791232.

The previous prime is 221242103. The next prime is 221242127. The reversal of 221242121 is 121242122.

It can be written as a sum of positive squares in 4 ways, for example, as 9859600 + 211382521 = 3140^2 + 14539^2 .

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 221242121 - 2¹⁴ = 221225737 is a prime.

It is a super-2 number, since 2×221242121² = 97896152209157282, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 221242121.

It is not an unprimeable number, because it can be changed into a prime (221242127) 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, 142055 + ... + 143603.

It is an arithmetic number, because the mean of its divisors is an integer number (27837225).

Almost surely, 2^221242121 is an apocalyptic number.

It is an amenable number.

221242121 is a deficient number, since it is larger than the sum of its proper divisors (1455679).

221242121 is a wasteful number, since it uses less digits than its factorization.

221242121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2395.

The product of its digits is 128, while the sum is 17.

The square root of 221242121 is about 14874.2099285979. The cubic root of 221242121 is about 604.8150708608.

Adding to 221242121 its reverse (121242122), we get a palindrome (342484243).

Subtracting from 221242121 its reverse (121242122), we obtain a palindrome (99999999).

The spelling of 221242121 in words is "two hundred twenty-one million, two hundred forty-two thousand, one hundred twenty-one".