201221212021 has 4 divisors (see below), whose sum is σ = 202099907500. Its totient is φ = 200342516544.

The previous prime is 201221212019. The next prime is 201221212039. The reversal of 201221212021 is 120212122102.

It is a happy number.

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 196946013796 + 4275198225 = 443786^2 + 65385^2 .

It is a cyclic number.

It is not a de Polignac number, because 201221212021 - 2¹ = 201221212019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 201221211986 and 201221212004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201221212051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 439347396 + ... + 439347853.

It is an arithmetic number, because the mean of its divisors is an integer number (50524976875).

Almost surely, 2^201221212021 is an apocalyptic number.

It is an amenable number.

201221212021 is a deficient number, since it is larger than the sum of its proper divisors (878695479).

201221212021 is an equidigital number, since it uses as much as digits as its factorization.

201221212021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 878695478.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 201221212021 its reverse (120212122102), we get a palindrome (321433334123).

The spelling of 201221212021 in words is "two hundred one billion, two hundred twenty-one million, two hundred twelve thousand, twenty-one".