21717216887 has 2 divisors, whose sum is σ = 21717216888. Its totient is φ = 21717216886.

The previous prime is 21717216793. The next prime is 21717216907. The reversal of 21717216887 is 78861271712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21717216887 - 2²⁶ = 21650108023 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21717213887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858608443 + 10858608444.

It is an arithmetic number, because the mean of its divisors is an integer number (10858608444).

Almost surely, 2^21717216887 is an apocalyptic number.

21717216887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717216887 is an equidigital number, since it uses as much as digits as its factorization.

21717216887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 526848, while the sum is 50.

The spelling of 21717216887 in words is "twenty-one billion, seven hundred seventeen million, two hundred sixteen thousand, eight hundred eighty-seven".