221211121 has 8 divisors (see below), whose sum is σ = 222883560. Its totient is φ = 219543552.

The previous prime is 221211083. The next prime is 221211127. The reversal of 221211121 is 121112122.

It can be written as a sum of positive squares in 4 ways, for example, as 43362225 + 177848896 = 6585^2 + 13336^2 .

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 221211121 - 2⁷ = 221210993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221211127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191281 + ... + 192433.

It is an arithmetic number, because the mean of its divisors is an integer number (27860445).

Almost surely, 2^221211121 is an apocalyptic number.

It is an amenable number.

221211121 is a deficient number, since it is larger than the sum of its proper divisors (1672439).

221211121 is a wasteful number, since it uses less digits than its factorization.

221211121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2435.

The product of its digits is 16, while the sum is 13.

The square root of 221211121 is about 14873.1678199367. The cubic root of 221211121 is about 604.7868210519.

Adding to 221211121 its reverse (121112122), we get a palindrome (342323243).

It can be divided in two parts, 22 and 1211121, that multiplied together give a palindrome (26644662).

The spelling of 221211121 in words is "two hundred twenty-one million, two hundred eleven thousand, one hundred twenty-one".