2121020221 has 2 divisors, whose sum is σ = 2121020222. Its totient is φ = 2121020220.

The previous prime is 2121020219. The next prime is 2121020267. The reversal of 2121020221 is 1220201212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1731392100 + 389628121 = 41610^2 + 19739^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121020221 - 2¹ = 2121020219 is a prime.

Together with 2121020219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2121020201) 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, 1060510110 + 1060510111.

It is an arithmetic number, because the mean of its divisors is an integer number (1060510111).

Almost surely, 2^2121020221 is an apocalyptic number.

It is an amenable number.

2121020221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121020221 is an equidigital number, since it uses as much as digits as its factorization.

2121020221 is an odious number, because the sum of its binary digits is odd.

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

The square root of 2121020221 is about 46054.5352924118. The cubic root of 2121020221 is about 1284.8376951359.

Adding to 2121020221 its reverse (1220201212), we get a palindrome (3341221433).

The spelling of 2121020221 in words is "two billion, one hundred twenty-one million, twenty thousand, two hundred twenty-one".