21717151664617 has 4 divisors (see below), whose sum is σ = 21855477471556. Its totient is φ = 21578825857680.

The previous prime is 21717151664599. The next prime is 21717151664639. The reversal of 21717151664617 is 71646615171712.

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 3520648042921 + 18196503621696 = 1876339^2 + 4265736^2 .

It is a cyclic number.

It is not a de Polignac number, because 21717151664617 - 2⁷ = 21717151664489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21717151694617) 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, 69162903234 + ... + 69162903547.

It is an arithmetic number, because the mean of its divisors is an integer number (5463869367889).

Almost surely, 2^{21717151664617} is an apocalyptic number.

It is an amenable number.

21717151664617 is a deficient number, since it is larger than the sum of its proper divisors (138325806939).

21717151664617 is a wasteful number, since it uses less digits than its factorization.

21717151664617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138325806938.

The product of its digits is 2963520, while the sum is 55.

The spelling of 21717151664617 in words is "twenty-one trillion, seven hundred seventeen billion, one hundred fifty-one million, six hundred sixty-four thousand, six hundred seventeen".