12821891 has 2 divisors, whose sum is σ = 12821892. Its totient is φ = 12821890.

The previous prime is 12821843. The next prime is 12821899. The reversal of 12821891 is 19812821.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12821891 is a prime.

It is not a weakly prime, because it can be changed into another prime (12821899) 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, 6410945 + 6410946.

It is an arithmetic number, because the mean of its divisors is an integer number (6410946).

Almost surely, 2^12821891 is an apocalyptic number.

12821891 is a deficient number, since it is larger than the sum of its proper divisors (1).

12821891 is an equidigital number, since it uses as much as digits as its factorization.

12821891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 32.

The square root of 12821891 is about 3580.7668173172. The cubic root of 12821891 is about 234.0546965912.

The spelling of 12821891 in words is "twelve million, eight hundred twenty-one thousand, eight hundred ninety-one".