21756485717 has 2 divisors, whose sum is σ = 21756485718. Its totient is φ = 21756485716.

The previous prime is 21756485693. The next prime is 21756485731. The reversal of 21756485717 is 71758465712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15728671396 + 6027814321 = 125414^2 + 77639^2 .

It is a cyclic number.

It is not a de Polignac number, because 21756485717 - 2⁸ = 21756485461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21756485417) 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, 10878242858 + 10878242859.

It is an arithmetic number, because the mean of its divisors is an integer number (10878242859).

Almost surely, 2^21756485717 is an apocalyptic number.

It is an amenable number.

21756485717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21756485717 is an equidigital number, since it uses as much as digits as its factorization.

21756485717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3292800, while the sum is 53.

The spelling of 21756485717 in words is "twenty-one billion, seven hundred fifty-six million, four hundred eighty-five thousand, seven hundred seventeen".