21033121013 has 4 divisors (see below), whose sum is σ = 21041614860. Its totient is φ = 21024627168.

The previous prime is 21033120971. The next prime is 21033121019. The reversal of 21033121013 is 31012133012.

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 9553498564 + 11479622449 = 97742^2 + 107143^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033121013 - 2¹⁴ = 21033104629 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21033120982 and 21033121000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033121019) 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, 4243208 + ... + 4248161.

It is an arithmetic number, because the mean of its divisors is an integer number (5260403715).

Almost surely, 2^21033121013 is an apocalyptic number.

It is an amenable number.

21033121013 is a deficient number, since it is larger than the sum of its proper divisors (8493847).

21033121013 is an equidigital number, since it uses as much as digits as its factorization.

21033121013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8493846.

The product of its (nonzero) digits is 108, while the sum is 17.

Adding to 21033121013 its reverse (31012133012), we get a palindrome (52045254025).

The spelling of 21033121013 in words is "twenty-one billion, thirty-three million, one hundred twenty-one thousand, thirteen".