21560317 has 2 divisors, whose sum is σ = 21560318. Its totient is φ = 21560316.

The previous prime is 21560291. The next prime is 21560321. The reversal of 21560317 is 71306512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15280281 + 6280036 = 3909^2 + 2506^2 .

It is a cyclic number.

It is not a de Polignac number, because 21560317 - 2¹⁵ = 21527549 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21560291 and 21560300.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21560327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10780158 + 10780159.

It is an arithmetic number, because the mean of its divisors is an integer number (10780159).

Almost surely, 2^21560317 is an apocalyptic number.

It is an amenable number.

21560317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21560317 is an equidigital number, since it uses as much as digits as its factorization.

21560317 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21560317 is about 4643.3088417636. The cubic root of 21560317 is about 278.3246771624.

Adding to 21560317 its reverse (71306512), we get a palindrome (92866829).

The spelling of 21560317 in words is "twenty-one million, five hundred sixty thousand, three hundred seventeen".