13661440 has 72 divisors (see below), whose sum is σ = 35283528. Its totient is φ = 5038080.

The previous prime is 13661429. The next prime is 13661447. The reversal of 13661440 is 4416631.

It can be written as a sum of positive squares in 4 ways, for example, as 1024 + 13660416 = 32^2 + 3696^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13661447) 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, 16230 + ... + 17050.

It is an arithmetic number, because the mean of its divisors is an integer number (490049).

Almost surely, 2^13661440 is an apocalyptic number.

13661440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 13661440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17641764).

13661440 is an abundant number, since it is smaller than the sum of its proper divisors (21622088).

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

13661440 is an equidigital number, since it uses as much as digits as its factorization.

13661440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 855 (or 841 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 13661440 is about 3696.1385255426. The cubic root of 13661440 is about 239.0555475074.

The spelling of 13661440 in words is "thirteen million, six hundred sixty-one thousand, four hundred forty".