21417317 has 2 divisors, whose sum is σ = 21417318. Its totient is φ = 21417316.

The previous prime is 21417307. The next prime is 21417323. The reversal of 21417317 is 71371412.

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., 21104836 + 312481 = 4594^2 + 559^2 .

It is a cyclic number.

It is not a de Polignac number, because 21417317 - 2¹² = 21413221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21417307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708658 + 10708659.

It is an arithmetic number, because the mean of its divisors is an integer number (10708659).

Almost surely, 2^21417317 is an apocalyptic number.

It is an amenable number.

21417317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21417317 is an equidigital number, since it uses as much as digits as its factorization.

21417317 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1176, while the sum is 26.

The square root of 21417317 is about 4627.8847219869. The cubic root of 21417317 is about 277.7079770870.

Adding to 21417317 its reverse (71371412), we get a palindrome (92788729).

The spelling of 21417317 in words is "twenty-one million, four hundred seventeen thousand, three hundred seventeen".