21678321717 has 36 divisors (see below), whose sum is σ = 34315837920. Its totient is φ = 13179699936.

The previous prime is 21678321713. The next prime is 21678321733. The reversal of 21678321717 is 71712387612.

It is not a de Polignac number, because 21678321717 - 2² = 21678321713 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678321713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 40384 + ... + 212102.

It is an arithmetic number, because the mean of its divisors is an integer number (953217720).

Almost surely, 2^21678321717 is an apocalyptic number.

It is an amenable number.

21678321717 is a deficient number, since it is larger than the sum of its proper divisors (12637516203).

21678321717 is a wasteful number, since it uses less digits than its factorization.

21678321717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171834 (or 171818 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The spelling of 21678321717 in words is "twenty-one billion, six hundred seventy-eight million, three hundred twenty-one thousand, seven hundred seventeen".