221100021221 has 4 divisors (see below), whose sum is σ = 223289130444. Its totient is φ = 218910912000.

The previous prime is 221100021187. The next prime is 221100021253. The reversal of 221100021221 is 122120001122.

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 161050518721 + 60049502500 = 401311^2 + 245050^2 .

It is a cyclic number.

It is not a de Polignac number, because 221100021221 - 2¹⁴ = 221100004837 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 = 221100021196 and 221100021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221100021721) 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, 1094554460 + ... + 1094554661.

It is an arithmetic number, because the mean of its divisors is an integer number (55822282611).

Almost surely, 2^221100021221 is an apocalyptic number.

It is an amenable number.

221100021221 is a deficient number, since it is larger than the sum of its proper divisors (2189109223).

221100021221 is a wasteful number, since it uses less digits than its factorization.

221100021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2189109222.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 221100021221 its reverse (122120001122), we get a palindrome (343220022343).

The spelling of 221100021221 in words is "two hundred twenty-one billion, one hundred million, twenty-one thousand, two hundred twenty-one".