21317703917 has 2 divisors, whose sum is σ = 21317703918. Its totient is φ = 21317703916.

The previous prime is 21317703881. The next prime is 21317703919. The reversal of 21317703917 is 71930771312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21314248036 + 3455881 = 145994^2 + 1859^2 .

It is a cyclic number.

It is not a de Polignac number, because 21317703917 - 2¹⁴ = 21317687533 is a prime.

Together with 21317703919, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21317703919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10658851958 + 10658851959.

It is an arithmetic number, because the mean of its divisors is an integer number (10658851959).

Almost surely, 2^21317703917 is an apocalyptic number.

It is an amenable number.

21317703917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21317703917 is an equidigital number, since it uses as much as digits as its factorization.

21317703917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55566, while the sum is 41.

The spelling of 21317703917 in words is "twenty-one billion, three hundred seventeen million, seven hundred three thousand, nine hundred seventeen".