15440 has 20 divisors (see below), whose sum is σ = 36084. Its totient is φ = 6144.

The previous prime is 15439. The next prime is 15443. The reversal of 15440 is 4451.

It can be written as a sum of positive squares in 2 ways, for example, as 4624 + 10816 = 68^2 + 104^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15443) 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, 17 + ... + 176.

2¹⁵⁴⁴⁰ is an apocalyptic number.

15440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15440 is an abundant number, since it is smaller than the sum of its proper divisors (20644).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18042).

15440 is a wasteful number, since it uses less digits than its factorization.

15440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 15440 is about 124.2577965361. The cubic root of 15440 is about 24.9009413471.

Adding to 15440 its reverse (4451), we get a palindrome (19891).

The spelling of 15440 in words is "fifteen thousand, four hundred forty".