201121000000021 has 4 divisors (see below), whose sum is σ = 204915735849132. Its totient is φ = 197326264150912.

The previous prime is 201121000000009. The next prime is 201121000000061. The reversal of 201121000000021 is 120000000121102.

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 149715168714225 + 51405831285796 = 12235815^2 + 7169786^2 .

It is a cyclic number.

It is not a de Polignac number, because 201121000000021 - 2⁹ = 201120999999509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 201120999999944 and 201121000000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201121000000061) 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, 1897367924476 + ... + 1897367924581.

It is an arithmetic number, because the mean of its divisors is an integer number (51228933962283).

Almost surely, 2^{201121000000021} is an apocalyptic number.

It is an amenable number.

201121000000021 is a deficient number, since it is larger than the sum of its proper divisors (3794735849111).

201121000000021 is an equidigital number, since it uses as much as digits as its factorization.

201121000000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3794735849110.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 201121000000021 its reverse (120000000121102), we get a palindrome (321121000121123).

The spelling of 201121000000021 in words is "two hundred one trillion, one hundred twenty-one billion, twenty-one", and thus it is an aban number.