221220001221 has 32 divisors (see below), whose sum is σ = 315346007040. Its totient is φ = 137533106304.

The previous prime is 221220001181. The next prime is 221220001231. The reversal of 221220001221 is 122100022122.

It is not a de Polignac number, because 221220001221 - 2¹¹ = 221219999173 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221220001221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221220001231) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5452416 + ... + 5492838.

It is an arithmetic number, because the mean of its divisors is an integer number (9854562720).

Almost surely, 2^221220001221 is an apocalyptic number.

It is an amenable number.

221220001221 is a deficient number, since it is larger than the sum of its proper divisors (94126005819).

221220001221 is a wasteful number, since it uses less digits than its factorization.

221220001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41945.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 221220001221 its reverse (122100022122), we get a palindrome (343320023343).

The spelling of 221220001221 in words is "two hundred twenty-one billion, two hundred twenty million, one thousand, two hundred twenty-one".