13931209 has 4 divisors (see below), whose sum is σ = 14194116. Its totient is φ = 13668304.

The previous prime is 13931191. The next prime is 13931219. The reversal of 13931209 is 90213931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90213931 = 1423 ⋅63397.

It can be written as a sum of positive squares in 2 ways, for example, as 3433609 + 10497600 = 1853^2 + 3240^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13931209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13931219) 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 in 3 ways as a sum of consecutive naturals, for example, 131374 + ... + 131479.

It is an arithmetic number, because the mean of its divisors is an integer number (3548529).

Almost surely, 2^13931209 is an apocalyptic number.

It is an amenable number.

13931209 is a deficient number, since it is larger than the sum of its proper divisors (262907).

13931209 is an equidigital number, since it uses as much as digits as its factorization.

13931209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262906.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 13931209 is about 3732.4534826304. The cubic root of 13931209 is about 240.6188254783.

The spelling of 13931209 in words is "thirteen million, nine hundred thirty-one thousand, two hundred nine".