15820 has 24 divisors (see below), whose sum is σ = 38304. Its totient is φ = 5376.

The previous prime is 15817. The next prime is 15823. The reversal of 15820 is 2851.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (15817) and next prime (15823).

It is an Ulam number.

15820 is an undulating number in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 15794 and 15803.

It is not an unprimeable number, because it can be changed into a prime (15823) 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, 84 + ... + 196.

It is an arithmetic number, because the mean of its divisors is an integer number (1596).

2¹⁵⁸²⁰ is an apocalyptic number.

15820 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 15820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19152).

15820 is an abundant number, since it is smaller than the sum of its proper divisors (22484).

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

15820 is a wasteful number, since it uses less digits than its factorization.

15820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 127 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 15820 is about 125.7775814682. Note that the first 3 decimals coincide. The cubic root of 15820 is about 25.1035703349.

It can be divided in two parts, 158 and 20, that multiplied together give a triangular number (3160 = T₇₉).

The spelling of 15820 in words is "fifteen thousand, eight hundred twenty".