12705209 has 4 divisors (see below), whose sum is σ = 13860240. Its totient is φ = 11550180.

The previous prime is 12705197. The next prime is 12705211. The reversal of 12705209 is 90250721.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90250721 = 11 ⋅8204611.

It is a cyclic number.

It is not a de Polignac number, because 12705209 - 2¹² = 12701113 is a prime.

It is a super-2 number, since 2×12705209² = 322844671467362, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12705229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 577499 + ... + 577520.

It is an arithmetic number, because the mean of its divisors is an integer number (3465060).

Almost surely, 2^12705209 is an apocalyptic number.

It is an amenable number.

12705209 is a deficient number, since it is larger than the sum of its proper divisors (1155031).

12705209 is a wasteful number, since it uses less digits than its factorization.

12705209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155030.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 12705209 is about 3564.4367016402. The cubic root of 12705209 is about 233.3425490691.

The spelling of 12705209 in words is "twelve million, seven hundred five thousand, two hundred nine".