12689821 has 2 divisors, whose sum is σ = 12689822. Its totient is φ = 12689820.

The previous prime is 12689797. The next prime is 12689857. The reversal of 12689821 is 12898621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12425625 + 264196 = 3525^2 + 514^2 .

It is an emirp because it is prime and its reverse (12898621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12689821 - 2⁷ = 12689693 is a prime.

It is a super-2 number, since 2×12689821² = 322063114024082, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12680821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6344910 + 6344911.

It is an arithmetic number, because the mean of its divisors is an integer number (6344911).

Almost surely, 2^12689821 is an apocalyptic number.

It is an amenable number.

12689821 is a deficient number, since it is larger than the sum of its proper divisors (1).

12689821 is an equidigital number, since it uses as much as digits as its factorization.

12689821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 37.

The square root of 12689821 is about 3562.2775018238. The cubic root of 12689821 is about 233.2483062079.

The spelling of 12689821 in words is "twelve million, six hundred eighty-nine thousand, eight hundred twenty-one".