1221010121221 has 32 divisors (see below), whose sum is σ = 1374898323456. Its totient is φ = 1074999240000.

The previous prime is 1221010121197. The next prime is 1221010121237. The reversal of 1221010121221 is 1221210101221.

It is a cyclic number.

It is not a de Polignac number, because 1221010121221 - 2¹⁷ = 1221009990149 is a prime.

It is a super-2 number, since 2×1221010121221² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221010121195 and 1221010121204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221010121621) 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, 9956946 + ... + 10078828.

It is an arithmetic number, because the mean of its divisors is an integer number (42965572608).

Almost surely, 2^{1221010121221} is an apocalyptic number.

1221010121221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221010121221 is a deficient number, since it is larger than the sum of its proper divisors (153888202235).

1221010121221 is a wasteful number, since it uses less digits than its factorization.

1221010121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122193.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 1221010121221 its reverse (1221210101221), we get a palindrome (2442220222442).

The spelling of 1221010121221 in words is "one trillion, two hundred twenty-one billion, ten million, one hundred twenty-one thousand, two hundred twenty-one".