21765828817 has 2 divisors, whose sum is σ = 21765828818. Its totient is φ = 21765828816.

The previous prime is 21765828787. The next prime is 21765828869. The reversal of 21765828817 is 71882856712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20093346001 + 1672482816 = 141751^2 + 40896^2 .

It is a cyclic number.

It is not a de Polignac number, because 21765828817 - 2¹⁵ = 21765796049 is a prime.

It is a super-3 number, since 3×21765828817³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21765828317) 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, 10882914408 + 10882914409.

It is an arithmetic number, because the mean of its divisors is an integer number (10882914409).

Almost surely, 2^21765828817 is an apocalyptic number.

It is an amenable number.

21765828817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765828817 is an equidigital number, since it uses as much as digits as its factorization.

21765828817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3010560, while the sum is 55.

The spelling of 21765828817 in words is "twenty-one billion, seven hundred sixty-five million, eight hundred twenty-eight thousand, eight hundred seventeen".