1221221021021 has 16 divisors (see below), whose sum is σ = 1245829939200. Its totient is φ = 1196671252608.

The previous prime is 1221221021011. The next prime is 1221221021047. The reversal of 1221221021021 is 1201201221221.

It is a cyclic number.

It is not a de Polignac number, because 1221221021021 - 2³⁴ = 1204041151837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221221021011) 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 15 ways as a sum of consecutive naturals, for example, 173490020 + ... + 173497058.

It is an arithmetic number, because the mean of its divisors is an integer number (77864371200).

Almost surely, 2^{1221221021021} is an apocalyptic number.

It is an amenable number.

1221221021021 is a deficient number, since it is larger than the sum of its proper divisors (24608918179).

1221221021021 is a wasteful number, since it uses less digits than its factorization.

1221221021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10748.

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

Adding to 1221221021021 its reverse (1201201221221), we get a palindrome (2422422242242).

The spelling of 1221221021021 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, twenty-one thousand, twenty-one".