2001221221121 has 2 divisors, whose sum is σ = 2001221221122. Its totient is φ = 2001221221120.

The previous prime is 2001221221037. The next prime is 2001221221151. The reversal of 2001221221121 is 1211221221002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1619001760000 + 382219461121 = 1272400^2 + 618239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2001221221121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2001221221121.

It is not a weakly prime, because it can be changed into another prime (2001221221151) 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, 1000610610560 + 1000610610561.

It is an arithmetic number, because the mean of its divisors is an integer number (1000610610561).

Almost surely, 2^{2001221221121} is an apocalyptic number.

It is an amenable number.

2001221221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001221221121 is an equidigital number, since it uses as much as digits as its factorization.

2001221221121 is an odious number, because the sum of its binary digits is odd.

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

Adding to 2001221221121 its reverse (1211221221002), we get a palindrome (3212442442123).

The spelling of 2001221221121 in words is "two trillion, one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".