2001121122221 has 4 divisors (see below), whose sum is σ = 2155053516252. Its totient is φ = 1847188728192.

The previous prime is 2001121122211. The next prime is 2001121122223. The reversal of 2001121122221 is 1222211211002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 962527777225 + 1038593344996 = 981085^2 + 1019114^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001121122221 - 2⁶ = 2001121122157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2001121122221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001121122223) 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 3 ways as a sum of consecutive naturals, for example, 76966196996 + ... + 76966197021.

It is an arithmetic number, because the mean of its divisors is an integer number (538763379063).

Almost surely, 2^{2001121122221} is an apocalyptic number.

It is an amenable number.

2001121122221 is a deficient number, since it is larger than the sum of its proper divisors (153932394031).

2001121122221 is a wasteful number, since it uses less digits than its factorization.

2001121122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153932394030.

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

Adding to 2001121122221 its reverse (1222211211002), we get a palindrome (3223332333223).

The spelling of 2001121122221 in words is "two trillion, one billion, one hundred twenty-one million, one hundred twenty-two thousand, two hundred twenty-one".