1221221010221 has 8 divisors (see below), whose sum is σ = 1314255205944. Its totient is φ = 1130542110720.

The previous prime is 1221221010181. The next prime is 1221221010223. The reversal of 1221221010221 is 1220101221221.

It can be written as a sum of positive squares in 4 ways, for example, as 129709321 + 1221091300900 = 11389^2 + 1105030^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221221010221 - 2³⁰ = 1220147268397 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221221010221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221221010223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 588822980 + ... + 588825053.

It is an arithmetic number, because the mean of its divisors is an integer number (164281900743).

Almost surely, 2^{1221221010221} is an apocalyptic number.

It is an amenable number.

1221221010221 is a deficient number, since it is larger than the sum of its proper divisors (93034195723).

1221221010221 is a wasteful number, since it uses less digits than its factorization.

1221221010221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1177648111.

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

Adding to 1221221010221 its reverse (1220101221221), we get a palindrome (2441322231442).

The spelling of 1221221010221 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, ten thousand, two hundred twenty-one".