21361742717 has 24 divisors (see below), whose sum is σ = 26394428664. Its totient is φ = 17178427392.

The previous prime is 21361742713. The next prime is 21361742737. The reversal of 21361742717 is 71724716312.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4991563801 + 16370178916 = 70651^2 + 127946^2 .

It is not a de Polignac number, because 21361742717 - 2² = 21361742713 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361742711) 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 in 23 ways as a sum of consecutive naturals, for example, 223613 + ... + 304509.

It is an arithmetic number, because the mean of its divisors is an integer number (1099767861).

Almost surely, 2^21361742717 is an apocalyptic number.

It is an amenable number.

21361742717 is a deficient number, since it is larger than the sum of its proper divisors (5032685947).

21361742717 is a wasteful number, since it uses less digits than its factorization.

21361742717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81245 (or 81238 counting only the distinct ones).

The product of its digits is 98784, while the sum is 41.

The spelling of 21361742717 in words is "twenty-one billion, three hundred sixty-one million, seven hundred forty-two thousand, seven hundred seventeen".