221203121 has 4 divisors (see below), whose sum is σ = 230820672. Its totient is φ = 211585572.

The previous prime is 221203117. The next prime is 221203123. The reversal of 221203121 is 121302122.

It is a happy number.

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 221203121 - 2² = 221203117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221203096 and 221203105.

It is not an unprimeable number, because it can be changed into a prime (221203123) 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, 4808741 + ... + 4808786.

It is an arithmetic number, because the mean of its divisors is an integer number (57705168).

Almost surely, 2^221203121 is an apocalyptic number.

It is an amenable number.

221203121 is a deficient number, since it is larger than the sum of its proper divisors (9617551).

221203121 is an equidigital number, since it uses as much as digits as its factorization.

221203121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9617550.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 221203121 is about 14872.8988768162. The cubic root of 221203121 is about 604.7795303502.

Adding to 221203121 its reverse (121302122), we get a palindrome (342505243).

Subtracting from 221203121 its reverse (121302122), we obtain a palindrome (99900999).

The spelling of 221203121 in words is "two hundred twenty-one million, two hundred three thousand, one hundred twenty-one".