21517216215413 has 8 divisors (see below), whose sum is σ = 21884076319800. Its totient is φ = 21150811558080.

The previous prime is 21517216215403. The next prime is 21517216215461. The reversal of 21517216215413 is 31451261271512.

It can be written as a sum of positive squares in 4 ways, for example, as 1023288026929 + 20493928188484 = 1011577^2 + 4527022^2 .

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 21517216215413 - 2³⁰ = 21516142473589 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 (21517216215403) 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, 113766470 + ... + 113955447.

It is an arithmetic number, because the mean of its divisors is an integer number (2735509539975).

Almost surely, 2^{21517216215413} is an apocalyptic number.

It is an amenable number.

21517216215413 is a deficient number, since it is larger than the sum of its proper divisors (366860104387).

21517216215413 is a wasteful number, since it uses less digits than its factorization.

21517216215413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227723527.

The product of its digits is 100800, while the sum is 41.

Adding to 21517216215413 its reverse (31451261271512), we get a palindrome (52968477486925).

The spelling of 21517216215413 in words is "twenty-one trillion, five hundred seventeen billion, two hundred sixteen million, two hundred fifteen thousand, four hundred thirteen".