13805509 has 4 divisors (see below), whose sum is σ = 14250880. Its totient is φ = 13360140.

The previous prime is 13805507. The next prime is 13805521. The reversal of 13805509 is 90550831.

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: 90550831 = 7 ⋅12935833.

It is a cyclic number.

It is not a de Polignac number, because 13805509 - 2¹ = 13805507 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 445339 = 13805509 / (1 + 3 + 8 + 0 + 5 + 5 + 0 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13805501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 222639 + ... + 222700.

It is an arithmetic number, because the mean of its divisors is an integer number (3562720).

Almost surely, 2^13805509 is an apocalyptic number.

It is an amenable number.

13805509 is a deficient number, since it is larger than the sum of its proper divisors (445371).

13805509 is an equidigital number, since it uses as much as digits as its factorization.

13805509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445370.

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 13805509 is about 3715.5765366898. The cubic root of 13805509 is about 239.8929441513.

It can be divided in two parts, 1380 and 5509, that added together give a square (6889 = 83²).

The spelling of 13805509 in words is "thirteen million, eight hundred five thousand, five hundred nine".