21103020121 has 4 divisors (see below), whose sum is σ = 21830710500. Its totient is φ = 20375329744.

The previous prime is 21103020097. The next prime is 21103020199. The reversal of 21103020121 is 12102030112.

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 4529290000 + 16573730121 = 67300^2 + 128739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103020121 - 2²³ = 21094631513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103029121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363845146 + ... + 363845203.

It is an arithmetic number, because the mean of its divisors is an integer number (5457677625).

Almost surely, 2^21103020121 is an apocalyptic number.

It is an amenable number.

21103020121 is a deficient number, since it is larger than the sum of its proper divisors (727690379).

21103020121 is an equidigital number, since it uses as much as digits as its factorization.

21103020121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 727690378.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21103020121 its reverse (12102030112), we get a palindrome (33205050233).

Subtracting from 21103020121 its reverse (12102030112), we obtain a palindrome (9000990009).

The spelling of 21103020121 in words is "twenty-one billion, one hundred three million, twenty thousand, one hundred twenty-one".