21506666344717 has 8 divisors (see below), whose sum is σ = 21514620829376. Its totient is φ = 21498712215552.

The previous prime is 21506666344703. The next prime is 21506666344741. The reversal of 21506666344717 is 71744366660512.

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-21506666344717 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 (21506666344417) 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, 212094733 + ... + 212196109.

It is an arithmetic number, because the mean of its divisors is an integer number (2689327603672).

Almost surely, 2^{21506666344717} is an apocalyptic number.

It is an amenable number.

21506666344717 is a deficient number, since it is larger than the sum of its proper divisors (7954484659).

21506666344717 is a wasteful number, since it uses less digits than its factorization.

21506666344717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177747.

The product of its (nonzero) digits is 30481920, while the sum is 58.

The spelling of 21506666344717 in words is "twenty-one trillion, five hundred six billion, six hundred sixty-six million, three hundred forty-four thousand, seven hundred seventeen".