15840 has 72 divisors (see below), whose sum is σ = 58968. Its totient is φ = 3840.

The previous prime is 15823. The next prime is 15859. The reversal of 15840 is 4851.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

15840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1435 + ... + 1445.

It is an arithmetic number, because the mean of its divisors is an integer number (819).

2¹⁵⁸⁴⁰ is an apocalyptic number.

15840 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 15840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29484).

15840 is an abundant number, since it is smaller than the sum of its proper divisors (43128).

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

15840 is a wasteful number, since it uses less digits than its factorization.

15840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 15840 is about 125.8570617804. The cubic root of 15840 is about 25.1141447129.

15840 divided by its product of nonzero digits (160) gives a palindrome (99).

The spelling of 15840 in words is "fifteen thousand, eight hundred forty".