221101212121 has 4 divisors (see below), whose sum is σ = 221108860852. Its totient is φ = 221093563392.

The previous prime is 221101212113. The next prime is 221101212139. The reversal of 221101212121 is 121212101122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 125131987600 + 95969224521 = 353740^2 + 309789^2 .

It is a cyclic number.

It is not a de Polignac number, because 221101212121 - 2³ = 221101212113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221101212095 and 221101212104.

It is not an unprimeable number, because it can be changed into a prime (221101212161) 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, 3780840 + ... + 3838873.

It is an arithmetic number, because the mean of its divisors is an integer number (55277215213).

Almost surely, 2^221101212121 is an apocalyptic number.

It is an amenable number.

221101212121 is a deficient number, since it is larger than the sum of its proper divisors (7648731).

221101212121 is an equidigital number, since it uses as much as digits as its factorization.

221101212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7648730.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 221101212121 its reverse (121212101122), we get a palindrome (342313313243).

The spelling of 221101212121 in words is "two hundred twenty-one billion, one hundred one million, two hundred twelve thousand, one hundred twenty-one".