21040340017 has 2 divisors, whose sum is σ = 21040340018. Its totient is φ = 21040340016.

The previous prime is 21040339997. The next prime is 21040340033. The reversal of 21040340017 is 71004304012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12028824976 + 9011515041 = 109676^2 + 94929^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21040340017 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21040340017.

It is not a weakly prime, because it can be changed into another prime (21040310017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520170008 + 10520170009.

It is an arithmetic number, because the mean of its divisors is an integer number (10520170009).

Almost surely, 2^21040340017 is an apocalyptic number.

It is an amenable number.

21040340017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040340017 is an equidigital number, since it uses as much as digits as its factorization.

21040340017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 22.

Adding to 21040340017 its reverse (71004304012), we get a palindrome (92044644029).

The spelling of 21040340017 in words is "twenty-one billion, forty million, three hundred forty thousand, seventeen".