1221221010181 has 2 divisors, whose sum is σ = 1221221010182. Its totient is φ = 1221221010180.

The previous prime is 1221221010127. The next prime is 1221221010223. The reversal of 1221221010181 is 1810101221221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1030243270081 + 190977740100 = 1015009^2 + 437010^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221221010181 - 2¹⁵ = 1221220977413 is a prime.

It is a super-2 number, since 2×1221221010181² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221221010281) 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, 610610505090 + 610610505091.

It is an arithmetic number, because the mean of its divisors is an integer number (610610505091).

Almost surely, 2^{1221221010181} is an apocalyptic number.

It is an amenable number.

1221221010181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221221010181 is an equidigital number, since it uses as much as digits as its factorization.

1221221010181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 22.

The spelling of 1221221010181 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, ten thousand, one hundred eighty-one".