12978209 has 4 divisors (see below), whose sum is σ = 13014720. Its totient is φ = 12941700.

The previous prime is 12978169. The next prime is 12978211. The reversal of 12978209 is 90287921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12978209 - 2¹² = 12974113 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12978239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17717 + ... + 18434.

It is an arithmetic number, because the mean of its divisors is an integer number (3253680).

Almost surely, 2^12978209 is an apocalyptic number.

It is an amenable number.

12978209 is a deficient number, since it is larger than the sum of its proper divisors (36511).

12978209 is an equidigital number, since it uses as much as digits as its factorization.

12978209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36510.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 12978209 is about 3602.5281400705. The cubic root of 12978209 is about 235.0020159779.

The spelling of 12978209 in words is "twelve million, nine hundred seventy-eight thousand, two hundred nine".