21011020121121 has 4 divisors (see below), whose sum is σ = 28014693494832. Its totient is φ = 14007346747412.

The previous prime is 21011020121093. The next prime is 21011020121153. The reversal of 21011020121121 is 12112102011012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21011020121121 - 2³⁰ = 21009946379297 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011020121121.

It is not an unprimeable number, because it can be changed into a prime (21011020121821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3501836686851 + ... + 3501836686856.

It is an arithmetic number, because the mean of its divisors is an integer number (7003673373708).

Almost surely, 2^{21011020121121} is an apocalyptic number.

It is an amenable number.

21011020121121 is a deficient number, since it is larger than the sum of its proper divisors (7003673373711).

21011020121121 is an equidigital number, since it uses as much as digits as its factorization.

21011020121121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003673373710.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21011020121121 its reverse (12112102011012), we get a palindrome (33123122132133).

The spelling of 21011020121121 in words is "twenty-one trillion, eleven billion, twenty million, one hundred twenty-one thousand, one hundred twenty-one".