21268723717 has 2 divisors, whose sum is σ = 21268723718. Its totient is φ = 21268723716.

The previous prime is 21268723703. The next prime is 21268723757. The reversal of 21268723717 is 71732786212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21106568961 + 162154756 = 145281^2 + 12734^2 .

It is a cyclic number.

It is not a de Polignac number, because 21268723717 - 2²⁷ = 21134505989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21268723757) 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, 10634361858 + 10634361859.

It is an arithmetic number, because the mean of its divisors is an integer number (10634361859).

Almost surely, 2^21268723717 is an apocalyptic number.

It is an amenable number.

21268723717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21268723717 is an equidigital number, since it uses as much as digits as its factorization.

21268723717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 395136, while the sum is 46.

The spelling of 21268723717 in words is "twenty-one billion, two hundred sixty-eight million, seven hundred twenty-three thousand, seven hundred seventeen".