201221002120021 has 16 divisors (see below), whose sum is σ = 217231834302000. Its totient is φ = 185286222194688.

The previous prime is 201221002120013. The next prime is 201221002120153. The reversal of 201221002120021 is 120021200122102.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 2883071557521 + 198337930562500 = 1697961^2 + 14083250^2 .

It is a cyclic number.

It is not a de Polignac number, because 201221002120021 - 2³ = 201221002120013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 201221002119977 and 201221002120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201221002121021) 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 15 ways as a sum of consecutive naturals, for example, 657756705 + ... + 658062553.

It is an arithmetic number, because the mean of its divisors is an integer number (13576989643875).

Almost surely, 2^{201221002120021} is an apocalyptic number.

It is an amenable number.

201221002120021 is a deficient number, since it is larger than the sum of its proper divisors (16010832181979).

201221002120021 is a wasteful number, since it uses less digits than its factorization.

201221002120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 430008.

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

Adding to 201221002120021 its reverse (120021200122102), we get a palindrome (321242202242123).

The spelling of 201221002120021 in words is "two hundred one trillion, two hundred twenty-one billion, two million, one hundred twenty thousand, twenty-one".