21201020121 has 8 divisors (see below), whose sum is σ = 28271311200. Its totient is φ = 14132371232.

The previous prime is 21201020117. The next prime is 21201020131. The reversal of 21201020121 is 12102010212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21201020121 - 2² = 21201020117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201020097 and 21201020106.

It is not an unprimeable number, because it can be changed into a prime (21201020131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 380100 + ... + 432293.

It is an arithmetic number, because the mean of its divisors is an integer number (3533913900).

Almost surely, 2^21201020121 is an apocalyptic number.

It is an amenable number.

21201020121 is a deficient number, since it is larger than the sum of its proper divisors (7070291079).

21201020121 is an equidigital number, since it uses as much as digits as its factorization.

21201020121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821095.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21201020121 its reverse (12102010212), we get a palindrome (33303030333).

Subtracting from 21201020121 its reverse (12102010212), we obtain a palindrome (9099009909).

The spelling of 21201020121 in words is "twenty-one billion, two hundred one million, twenty thousand, one hundred twenty-one".