13809021 has 4 divisors (see below), whose sum is σ = 18412032. Its totient is φ = 9206012.

The previous prime is 13809013. The next prime is 13809031. The reversal of 13809021 is 12090831.

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: 12090831 = 3 ⋅4030277.

It is a cyclic number.

It is not a de Polignac number, because 13809021 - 2³ = 13809013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 13808982 and 13809000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13809011) 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, 2301501 + ... + 2301506.

It is an arithmetic number, because the mean of its divisors is an integer number (4603008).

Almost surely, 2^13809021 is an apocalyptic number.

It is an amenable number.

13809021 is a deficient number, since it is larger than the sum of its proper divisors (4603011).

13809021 is an equidigital number, since it uses as much as digits as its factorization.

13809021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4603010.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 13809021 is about 3716.0491116238. The cubic root of 13809021 is about 239.9132846445.

Adding to 13809021 its reverse (12090831), we get a palindrome (25899852).

It can be divided in two parts, 1380 and 9021, that added together give a palindrome (10401).

The spelling of 13809021 in words is "thirteen million, eight hundred nine thousand, twenty-one".