21241312121 has 8 divisors (see below), whose sum is σ = 21520189704. Its totient is φ = 20963779200.

The previous prime is 21241312087. The next prime is 21241312193. The reversal of 21241312121 is 12121314212.

It can be written as a sum of positive squares in 4 ways, for example, as 8486094400 + 12755217721 = 92120^2 + 112939^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21241312121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21241312093 and 21241312102.

It is not an unprimeable number, because it can be changed into a prime (21241312621) 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, 304346 + ... + 367571.

It is an arithmetic number, because the mean of its divisors is an integer number (2690023713).

Almost surely, 2^21241312121 is an apocalyptic number.

It is an amenable number.

21241312121 is a deficient number, since it is larger than the sum of its proper divisors (278877583).

21241312121 is a wasteful number, since it uses less digits than its factorization.

21241312121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 672331.

The product of its digits is 192, while the sum is 20.

Adding to 21241312121 its reverse (12121314212), we get a palindrome (33362626333).

The spelling of 21241312121 in words is "twenty-one billion, two hundred forty-one million, three hundred twelve thousand, one hundred twenty-one".