21810684317 has 2 divisors, whose sum is σ = 21810684318. Its totient is φ = 21810684316.

The previous prime is 21810684253. The next prime is 21810684319. The reversal of 21810684317 is 71348601812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21577847236 + 232837081 = 146894^2 + 15259^2 .

It is a cyclic number.

It is not a de Polignac number, because 21810684317 - 2⁶ = 21810684253 is a prime.

Together with 21810684319, 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 (21810684319) 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 as a sum of consecutive naturals, namely, 10905342158 + 10905342159.

It is an arithmetic number, because the mean of its divisors is an integer number (10905342159).

Almost surely, 2^21810684317 is an apocalyptic number.

It is an amenable number.

21810684317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21810684317 is an equidigital number, since it uses as much as digits as its factorization.

21810684317 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64512, while the sum is 41.

The spelling of 21810684317 in words is "twenty-one billion, eight hundred ten million, six hundred eighty-four thousand, three hundred seventeen".