21521130555013 has 4 divisors (see below), whose sum is σ = 22046036178348. Its totient is φ = 20996224931680.

The previous prime is 21521130555011. The next prime is 21521130555053. The reversal of 21521130555013 is 31055503112512.

It is a happy number.

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 11001474021409 + 10519656533604 = 3316847^2 + 3243402^2 .

It is a cyclic number.

It is not a de Polignac number, because 21521130555013 - 2¹ = 21521130555011 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21521130555013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521130555011) 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, 262452811606 + ... + 262452811687.

It is an arithmetic number, because the mean of its divisors is an integer number (5511509044587).

Almost surely, 2^{21521130555013} is an apocalyptic number.

It is an amenable number.

21521130555013 is a deficient number, since it is larger than the sum of its proper divisors (524905623335).

21521130555013 is an equidigital number, since it uses as much as digits as its factorization.

21521130555013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524905623334.

The product of its (nonzero) digits is 22500, while the sum is 34.

Adding to 21521130555013 its reverse (31055503112512), we get a palindrome (52576633667525).

The spelling of 21521130555013 in words is "twenty-one trillion, five hundred twenty-one billion, one hundred thirty million, five hundred fifty-five thousand, thirteen".