1221100201221 has 4 divisors (see below), whose sum is σ = 1628133601632. Its totient is φ = 814066800812.

The previous prime is 1221100201207. The next prime is 1221100201229. The reversal of 1221100201221 is 1221020011221.

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 1221100201221 - 2¹⁹ = 1221099676933 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221100201221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221100201229) 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, 203516700201 + ... + 203516700206.

It is an arithmetic number, because the mean of its divisors is an integer number (407033400408).

Almost surely, 2^{1221100201221} is an apocalyptic number.

It is an amenable number.

1221100201221 is a deficient number, since it is larger than the sum of its proper divisors (407033400411).

1221100201221 is an equidigital number, since it uses as much as digits as its factorization.

1221100201221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407033400410.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 1221100201221 its reverse (1221020011221), we get a palindrome (2442120212442).

The spelling of 1221100201221 in words is "one trillion, two hundred twenty-one billion, one hundred million, two hundred one thousand, two hundred twenty-one".