21715505506717 has 8 divisors (see below), whose sum is σ = 23924193286752. Its totient is φ = 19545909546000.

The previous prime is 21715505506711. The next prime is 21715505506757. The reversal of 21715505506717 is 71760550551712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21715505506717 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21715505506711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9772953663 + ... + 9772955884.

It is an arithmetic number, because the mean of its divisors is an integer number (2990524160844).

Almost surely, 2^{21715505506717} is an apocalyptic number.

It is an amenable number.

21715505506717 is a deficient number, since it is larger than the sum of its proper divisors (2208687780035).

21715505506717 is a wasteful number, since it uses less digits than its factorization.

21715505506717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19545909659.

The product of its (nonzero) digits is 2572500, while the sum is 52.

It can be divided in two parts, 21715505 and 506717, that added together give a palindrome (22222222).

The spelling of 21715505506717 in words is "twenty-one trillion, seven hundred fifteen billion, five hundred five million, five hundred six thousand, seven hundred seventeen".