13866821 has 2 divisors, whose sum is σ = 13866822. Its totient is φ = 13866820.

The previous prime is 13866793. The next prime is 13866841. The reversal of 13866821 is 12866831.

13866821 is nontrivially palindromic in base 3.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8916196 + 4950625 = 2986^2 + 2225^2 .

It is an emirp because it is prime and its reverse (12866831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13866821 - 2⁶ = 13866757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13866841) 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, 6933410 + 6933411.

It is an arithmetic number, because the mean of its divisors is an integer number (6933411).

Almost surely, 2^13866821 is an apocalyptic number.

It is an amenable number.

13866821 is a deficient number, since it is larger than the sum of its proper divisors (1).

13866821 is an equidigital number, since it uses as much as digits as its factorization.

13866821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 35.

The square root of 13866821 is about 3723.8180675216. The cubic root of 13866821 is about 240.2475512850.

The spelling of 13866821 in words is "thirteen million, eight hundred sixty-six thousand, eight hundred twenty-one".