1221100021221 has 48 divisors (see below), whose sum is σ = 1747033848000. Its totient is φ = 758462625792.

The previous prime is 1221100021181. The next prime is 1221100021241. The reversal of 1221100021221 is 1221200011221.

It is not a de Polignac number, because 1221100021221 - 2¹⁴ = 1221100004837 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221100021221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221100021241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 42044521 + ... + 42073553.

It is an arithmetic number, because the mean of its divisors is an integer number (36396538500).

Almost surely, 2^{1221100021221} is an apocalyptic number.

It is an amenable number.

1221100021221 is a deficient number, since it is larger than the sum of its proper divisors (525933826779).

1221100021221 is a wasteful number, since it uses less digits than its factorization.

1221100021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29558 (or 29541 counting only the distinct ones).

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

Adding to 1221100021221 its reverse (1221200011221), we get a palindrome (2442300032442).

The spelling of 1221100021221 in words is "one trillion, two hundred twenty-one billion, one hundred million, twenty-one thousand, two hundred twenty-one".