221201211221 has 4 divisors (see below), whose sum is σ = 221202177612. Its totient is φ = 221200244832.

The previous prime is 221201211199. The next prime is 221201211239. The reversal of 221201211221 is 122112102122.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 43020982225 + 178180228996 = 207415^2 + 422114^2 .

It is a cyclic number.

It is not a de Polignac number, because 221201211221 - 2¹⁸ = 221200949077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221201211221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221201211271) 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, 75401 + ... + 669393.

It is an arithmetic number, because the mean of its divisors is an integer number (55300544403).

Almost surely, 2^221201211221 is an apocalyptic number.

It is an amenable number.

221201211221 is a deficient number, since it is larger than the sum of its proper divisors (966391).

221201211221 is an equidigital number, since it uses as much as digits as its factorization.

221201211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 966390.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 221201211221 its reverse (122112102122), we get a palindrome (343313313343).

The spelling of 221201211221 in words is "two hundred twenty-one billion, two hundred one million, two hundred eleven thousand, two hundred twenty-one".