21717205183871 has 2 divisors, whose sum is σ = 21717205183872. Its totient is φ = 21717205183870.

The previous prime is 21717205183811. The next prime is 21717205183967. The reversal of 21717205183871 is 17838150271712.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21717205183871 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21717205183811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858602591935 + 10858602591936.

It is an arithmetic number, because the mean of its divisors is an integer number (10858602591936).

Almost surely, 2^{21717205183871} is an apocalyptic number.

21717205183871 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717205183871 is an equidigital number, since it uses as much as digits as its factorization.

21717205183871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1317120, while the sum is 53.

The spelling of 21717205183871 in words is "twenty-one trillion, seven hundred seventeen billion, two hundred five million, one hundred eighty-three thousand, eight hundred seventy-one".