21021121013 has 4 divisors (see below), whose sum is σ = 21023363628. Its totient is φ = 21018878400.

The previous prime is 21021121007. The next prime is 21021121081. The reversal of 21021121013 is 31012112012.

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 18186410449 + 2834710564 = 134857^2 + 53242^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021121013 - 2³⁰ = 19947379189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021121313) 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, 1107188 + ... + 1126013.

It is an arithmetic number, because the mean of its divisors is an integer number (5255840907).

Almost surely, 2^21021121013 is an apocalyptic number.

It is an amenable number.

21021121013 is a deficient number, since it is larger than the sum of its proper divisors (2242615).

21021121013 is an equidigital number, since it uses as much as digits as its factorization.

21021121013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2242614.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21021121013 its reverse (31012112012), we get a palindrome (52033233025).

Subtracting 21021121013 from its reverse (31012112012), we obtain a palindrome (9990990999).

The spelling of 21021121013 in words is "twenty-one billion, twenty-one million, one hundred twenty-one thousand, thirteen".