13890809 has 4 divisors (see below), whose sum is σ = 13900404. Its totient is φ = 13881216.

The previous prime is 13890791. The next prime is 13890817. The reversal of 13890809 is 90809831.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90809831 = 7 ⋅12972833.

It can be written as a sum of positive squares in 2 ways, for example, as 2310400 + 11580409 = 1520^2 + 3403^2 .

It is a cyclic number.

It is not a de Polignac number, because 13890809 - 2⁸ = 13890553 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (13890839) 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, 2132 + ... + 5685.

It is an arithmetic number, because the mean of its divisors is an integer number (3475101).

Almost surely, 2^13890809 is an apocalyptic number.

It is an amenable number.

13890809 is a deficient number, since it is larger than the sum of its proper divisors (9595).

13890809 is an equidigital number, since it uses as much as digits as its factorization.

13890809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9594.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 13890809 is about 3727.0375635349. The cubic root of 13890809 is about 240.3860049918.

The spelling of 13890809 in words is "thirteen million, eight hundred ninety thousand, eight hundred nine".