21040434617 has 2 divisors, whose sum is σ = 21040434618. Its totient is φ = 21040434616.

The previous prime is 21040434581. The next prime is 21040434629. The reversal of 21040434617 is 71643404012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17203994896 + 3836439721 = 131164^2 + 61939^2 .

It is a cyclic number.

It is not a de Polignac number, because 21040434617 - 2¹⁴ = 21040418233 is a prime.

It is not a weakly prime, because it can be changed into another prime (21040434637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520217308 + 10520217309.

It is an arithmetic number, because the mean of its divisors is an integer number (10520217309).

Almost surely, 2^21040434617 is an apocalyptic number.

It is an amenable number.

21040434617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040434617 is an equidigital number, since it uses as much as digits as its factorization.

21040434617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 32.

Adding to 21040434617 its reverse (71643404012), we get a palindrome (92683838629).

The spelling of 21040434617 in words is "twenty-one billion, forty million, four hundred thirty-four thousand, six hundred seventeen".