21018317 has 2 divisors, whose sum is σ = 21018318. Its totient is φ = 21018316.

The previous prime is 21018293. The next prime is 21018323. The reversal of 21018317 is 71381012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20967241 + 51076 = 4579^2 + 226^2 .

It is a cyclic number.

It is not a de Polignac number, because 21018317 - 2¹⁴ = 21001933 is a prime.

It is a Chen prime.

It is equal to p_1331069 and since 21018317 and 1331069 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 21018292 and 21018301.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21018397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509158 + 10509159.

It is an arithmetic number, because the mean of its divisors is an integer number (10509159).

Almost surely, 2^21018317 is an apocalyptic number.

It is an amenable number.

21018317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21018317 is an equidigital number, since it uses as much as digits as its factorization.

21018317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21018317 is about 4584.5738078910. The cubic root of 21018317 is about 275.9726089529.

Adding to 21018317 its reverse (71381012), we get a palindrome (92399329).

The spelling of 21018317 in words is "twenty-one million, eighteen thousand, three hundred seventeen".