21322517 has 4 divisors (see below), whose sum is σ = 21361356. Its totient is φ = 21283680.

The previous prime is 21322493. The next prime is 21322547. The reversal of 21322517 is 71522312.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12117361 + 9205156 = 3481^2 + 3034^2 .

It is a cyclic number.

It is not a de Polignac number, because 21322517 - 2¹⁰ = 21321493 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21322492 and 21322501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21322547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18584 + ... + 19697.

It is an arithmetic number, because the mean of its divisors is an integer number (5340339).

Almost surely, 2^21322517 is an apocalyptic number.

It is an amenable number.

21322517 is a deficient number, since it is larger than the sum of its proper divisors (38839).

21322517 is an equidigital number, since it uses as much as digits as its factorization.

21322517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38838.

The product of its digits is 840, while the sum is 23.

The square root of 21322517 is about 4617.6311026326. The cubic root of 21322517 is about 277.2976291496.

Adding to 21322517 its reverse (71522312), we get a palindrome (92844829).

The spelling of 21322517 in words is "twenty-one million, three hundred twenty-two thousand, five hundred seventeen".