2001122221 has 6 divisors (see below), whose sum is σ = 2327836110. Its totient is φ = 1715247576.

The previous prime is 2001122143. The next prime is 2001122251. The reversal of 2001122221 is 1222211002.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1692417321 + 308704900 = 41139^2 + 17570^2 .

It is not a de Polignac number, because 2001122221 - 2⁷ = 2001122093 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 (2001122251) 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 5 ways as a sum of consecutive naturals, for example, 20419566 + ... + 20419663.

It is an arithmetic number, because the mean of its divisors is an integer number (387972685).

Almost surely, 2^2001122221 is an apocalyptic number.

It is an amenable number.

2001122221 is a deficient number, since it is larger than the sum of its proper divisors (326713889).

2001122221 is an equidigital number, since it uses as much as digits as its factorization.

2001122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40839243 (or 40839236 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 2001122221 is about 44733.9046026613. The cubic root of 2001122221 is about 1260.1566574765.

Adding to 2001122221 its reverse (1222211002), we get a palindrome (3223333223).

The spelling of 2001122221 in words is "two billion, one million, one hundred twenty-two thousand, two hundred twenty-one".