21735091817 has 2 divisors, whose sum is σ = 21735091818. Its totient is φ = 21735091816.

The previous prime is 21735091801. The next prime is 21735091867. The reversal of 21735091817 is 71819053712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18256333456 + 3478758361 = 135116^2 + 58981^2 .

It is a cyclic number.

It is not a de Polignac number, because 21735091817 - 2⁴ = 21735091801 is a prime.

It is a super-2 number, since 2×21735091817² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21735091867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10867545908 + 10867545909.

It is an arithmetic number, because the mean of its divisors is an integer number (10867545909).

Almost surely, 2^21735091817 is an apocalyptic number.

It is an amenable number.

21735091817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21735091817 is an equidigital number, since it uses as much as digits as its factorization.

21735091817 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 105840, while the sum is 44.

The spelling of 21735091817 in words is "twenty-one billion, seven hundred thirty-five million, ninety-one thousand, eight hundred seventeen".