13638209 has 4 divisors (see below), whose sum is σ = 14687316. Its totient is φ = 12589104.

The previous prime is 13638203. The next prime is 13638211. The reversal of 13638209 is 90283631.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7997584 + 5640625 = 2828^2 + 2375^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13638209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13638203) 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, 524534 + ... + 524559.

It is an arithmetic number, because the mean of its divisors is an integer number (3671829).

Almost surely, 2^13638209 is an apocalyptic number.

It is an amenable number.

13638209 is a deficient number, since it is larger than the sum of its proper divisors (1049107).

13638209 is a wasteful number, since it uses less digits than its factorization.

13638209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1049106.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 13638209 is about 3692.9945843448. The cubic root of 13638209 is about 238.9199676009.

The spelling of 13638209 in words is "thirteen million, six hundred thirty-eight thousand, two hundred nine".