1221210028121 has 2 divisors, whose sum is σ = 1221210028122. Its totient is φ = 1221210028120.

The previous prime is 1221210028043. The next prime is 1221210028141. The reversal of 1221210028121 is 1218200121221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 722858744521 + 498351283600 = 850211^2 + 705940^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221210028121 is a prime.

It is a super-2 number, since 2×1221210028121² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221210028141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610605014060 + 610605014061.

It is an arithmetic number, because the mean of its divisors is an integer number (610605014061).

Almost surely, 2^{1221210028121} is an apocalyptic number.

It is an amenable number.

1221210028121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221210028121 is an equidigital number, since it uses as much as digits as its factorization.

1221210028121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 23.

Adding to 1221210028121 its reverse (1218200121221), we get a palindrome (2439410149342).

The spelling of 1221210028121 in words is "one trillion, two hundred twenty-one billion, two hundred ten million, twenty-eight thousand, one hundred twenty-one".