21717553901671 has 2 divisors, whose sum is σ = 21717553901672. Its totient is φ = 21717553901670.

The previous prime is 21717553901629. The next prime is 21717553901779. The reversal of 21717553901671 is 17610935571712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21717553901671 - 2⁴¹ = 19518530646119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21717553991671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858776950835 + 10858776950836.

It is an arithmetic number, because the mean of its divisors is an integer number (10858776950836).

Almost surely, 2^{21717553901671} is an apocalyptic number.

21717553901671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717553901671 is an equidigital number, since it uses as much as digits as its factorization.

21717553901671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2778300, while the sum is 55.

The spelling of 21717553901671 in words is "twenty-one trillion, seven hundred seventeen billion, five hundred fifty-three million, nine hundred one thousand, six hundred seventy-one".