2001021011221 has 4 divisors (see below), whose sum is σ = 2001024042444. Its totient is φ = 2001017980000.

The previous prime is 2001021011191. The next prime is 2001021011239. The reversal of 2001021011221 is 1221101201002.

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 152481659121 + 1848539352100 = 390489^2 + 1359610^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001021011221 - 2⁵ = 2001021011189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001021017221) 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 in 3 ways as a sum of consecutive naturals, for example, 58360 + ... + 2001361.

It is an arithmetic number, because the mean of its divisors is an integer number (500256010611).

Almost surely, 2^{2001021011221} is an apocalyptic number.

It is an amenable number.

2001021011221 is a deficient number, since it is larger than the sum of its proper divisors (3031223).

2001021011221 is an equidigital number, since it uses as much as digits as its factorization.

2001021011221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3031222.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 2001021011221 its reverse (1221101201002), we get a palindrome (3222122212223).

The spelling of 2001021011221 in words is "two trillion, one billion, twenty-one million, eleven thousand, two hundred twenty-one".