12720209 has 6 divisors (see below), whose sum is σ = 13053894. Its totient is φ = 12387680.

The previous prime is 12720187. The next prime is 12720229. The reversal of 12720209 is 90202721.

It can be written as a sum of positive squares in 3 ways, for example, as 1697809 + 11022400 = 1303^2 + 3320^2 .

It is not a de Polignac number, because 12720209 - 2¹² = 12716113 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12720229) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22559 + ... + 23115.

It is an arithmetic number, because the mean of its divisors is an integer number (2175649).

Almost surely, 2^12720209 is an apocalyptic number.

It is an amenable number.

12720209 is a deficient number, since it is larger than the sum of its proper divisors (333685).

12720209 is an frugal number, since it uses more digits than its factorization.

12720209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155 (or 598 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 12720209 is about 3566.5402002501. The cubic root of 12720209 is about 233.4343424350.

The spelling of 12720209 in words is "twelve million, seven hundred twenty thousand, two hundred nine".