221021121 has 4 divisors (see below), whose sum is σ = 294694832. Its totient is φ = 147347412.

The previous prime is 221021111. The next prime is 221021137. The reversal of 221021121 is 121120122.

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 not a de Polignac number, because 221021121 - 2⁵ = 221021089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221021097 and 221021106.

It is not an unprimeable number, because it can be changed into a prime (221021111) 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, 36836851 + ... + 36836856.

It is an arithmetic number, because the mean of its divisors is an integer number (73673708).

Almost surely, 2^221021121 is an apocalyptic number.

It is an amenable number.

221021121 is a deficient number, since it is larger than the sum of its proper divisors (73673711).

221021121 is an equidigital number, since it uses as much as digits as its factorization.

221021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73673710.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 221021121 is about 14866.7791064507. The cubic root of 221021121 is about 604.6136193761.

Adding to 221021121 its reverse (121120122), we get a palindrome (342141243).

Subtracting from 221021121 its reverse (121120122), we obtain a palindrome (99900999).

The spelling of 221021121 in words is "two hundred twenty-one million, twenty-one thousand, one hundred twenty-one".