21012016605517 has 4 divisors (see below), whose sum is σ = 24013733263456. Its totient is φ = 18010299947580.

The previous prime is 21012016605497. The next prime is 21012016605527. The reversal of 21012016605517 is 71550661021012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21012016605517 - 2¹¹ = 21012016603469 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 (21012016605527) 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, 1500858328959 + ... + 1500858328972.

It is an arithmetic number, because the mean of its divisors is an integer number (6003433315864).

Almost surely, 2^{21012016605517} is an apocalyptic number.

It is an amenable number.

21012016605517 is a deficient number, since it is larger than the sum of its proper divisors (3001716657939).

21012016605517 is an equidigital number, since it uses as much as digits as its factorization.

21012016605517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3001716657938.

The product of its (nonzero) digits is 25200, while the sum is 37.

Adding to 21012016605517 its reverse (71550661021012), we get a palindrome (92562677626529).

The spelling of 21012016605517 in words is "twenty-one trillion, twelve billion, sixteen million, six hundred five thousand, five hundred seventeen".