13581220 has 24 divisors (see below), whose sum is σ = 29292984. Its totient is φ = 5285376.

The previous prime is 13581199. The next prime is 13581229. The reversal of 13581220 is 2218531.

It can be written as a sum of positive squares in 4 ways, for example, as 736164 + 12845056 = 858^2 + 3584^2 .

It is a junction number, because it is equal to n+sod(n) for n = 13581191 and 13581200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13581229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8437 + ... + 9916.

It is an arithmetic number, because the mean of its divisors is an integer number (1220541).

Almost surely, 2^13581220 is an apocalyptic number.

13581220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

13581220 is an abundant number, since it is smaller than the sum of its proper divisors (15711764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13581220 is a wasteful number, since it uses less digits than its factorization.

13581220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18399 (or 18397 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 13581220 is about 3685.2706820531. The cubic root of 13581220 is about 238.5867171153.

Adding to 13581220 its reverse (2218531), we get a palindrome (15799751).

The spelling of 13581220 in words is "thirteen million, five hundred eighty-one thousand, two hundred twenty".