21182717 has 2 divisors, whose sum is σ = 21182718. Its totient is φ = 21182716.

The previous prime is 21182659. The next prime is 21182719. The reversal of 21182717 is 71728112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21031396 + 151321 = 4586^2 + 389^2 .

It is a cyclic number.

It is not a de Polignac number, because 21182717 - 2⁸ = 21182461 is a prime.

Together with 21182719, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21182717.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21182719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10591358 + 10591359.

It is an arithmetic number, because the mean of its divisors is an integer number (10591359).

Almost surely, 2^21182717 is an apocalyptic number.

It is an amenable number.

21182717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21182717 is an equidigital number, since it uses as much as digits as its factorization.

21182717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1568, while the sum is 29.

The square root of 21182717 is about 4602.4685767531. The cubic root of 21182717 is about 276.6902705624.

It can be divided in two parts, 211 and 82717, that added together give a palindrome (82928).

The spelling of 21182717 in words is "twenty-one million, one hundred eighty-two thousand, seven hundred seventeen".