15540 has 48 divisors (see below), whose sum is σ = 51072. Its totient is φ = 3456.

The previous prime is 15527. The next prime is 15541. The reversal of 15540 is 4551.

15540 = T₂₉ + T₃₀ + ... + T₄₈.

It is a Harshad number since it is a multiple of its sum of digits (15).

15540 is a Rhonda number in base 9.

It is a nialpdrome in base 7.

It is a Saint-Exupery number, since it is equal to the product of the sides of a Pythagorean triangle: 37 × 35 × 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15541) by changing a digit.

15540 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 15 ways as a sum of consecutive naturals, for example, 402 + ... + 438.

It is an arithmetic number, because the mean of its divisors is an integer number (1064).

2¹⁵⁵⁴⁰ is an apocalyptic number.

15540 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 15540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25536).

15540 is an abundant number, since it is smaller than the sum of its proper divisors (35532).

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

15540 is a wasteful number, since it uses less digits than its factorization.

15540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 15540 is about 124.6595363380. The cubic root of 15540 is about 24.9545842129.

It can be divided in two parts, 15 and 540, that multiplied together give a square (8100 = 90²).

The spelling of 15540 in words is "fifteen thousand, five hundred forty".